So, using my quest editor, I decided to check the error checker by checking the quests that come with the game. Here is some of the results of the check.

In Quest_TheHaunter, there is a reference to a Plaguestalker, There is an inappropriate capitalization. 

This should read as follows

               <Encounter>
                    <Liklihood>100</Liklihood>
                    <BattleIdentifier>Haunter</BattleIdentifier>
                    <WillRespawn>0</WillRespawn>
                    <WanderingRadius>0</WanderingRadius>
                    <UnitInstance>
                        <UnitType>Haunter</UnitType>
                        <Level>7</Level>
                    </UnitInstance>
                    <UnitInstance>
                        <UnitType>Plaguestalker</UnitType>
                        <Level>5</Level>
                    </UnitInstance>
                    <UnitInstance>
                        <UnitType>Plaguestalker</UnitType>
                        <Level>5</Level>
                    </UnitInstance>
                </Encounter>

The quest works fine with the error, but as your fixing up the quests, why not fix up these quick things.

In Quest_TreasureMap, there is a missreference between two goodie huts. It spawns one goodie hut, but wants you to clear another, leads to some problems.

            <Treasure>
                <GameModifier>
                    <ModType>Map</ModType>
                    <Attribute>CreateGoodieHut</Attribute>
                    <StrVal>Treasure Chest</StrVal>
                    <Unitclass>GH_Quest_Chest</Unitclass>
                    <Radius>6</Radius>
                </GameModifier>
            </Treasure>
            <QuestConditionDef>
                <Objective>
                    <Icon>Mana_32.png</Icon>
                    <Text>Find the Treasure Chest.</Text>
                     <IsOptional>0</IsOptional>
                </Objective>
                <Class>Success</Class>
                <Type>ClearGoodieHut</Type>
                <TextData>GH_Quest_Chest</TextData>
                <Flag>RevealTarget</Flag>
            </QuestConditionDef>

The fix is to match up the tags, as I've done above.

In Quest_Persecution, there is a typo reference (misspelled name call) (It was Unit_Peasant_Altarien)

<Encounter>
                    <Liklihood>100</Liklihood>
                    <BattleIdentifier>Unit_Defender_Tarth</BattleIdentifier>
                    <WillRespawn>0</WillRespawn>
                    <WanderingRadius>0</WanderingRadius>
                    <UnitInstance>
                        <UnitType>Unit_Defender_Tarth</UnitType>
                        <UnitName>Rioting Mob</UnitName>
                        <UnitGroupingType>UnitGroupingType_Group</UnitGroupingType>
                        <Level>3</Level>
                    </UnitInstance>
                    <UnitInstance>
                        <UnitType>Unit_Peasant_Ironeer</UnitType>
                        <UnitName>Rioting Mob</UnitName>
                        <UnitGroupingType>UnitGroupingType_Group</UnitGroupingType>
                        <Level>2</Level>
                    </UnitInstance>
                    <UnitInstance>
                        <UnitType>Unit_Peasant_Altarian</UnitType>
                        <UnitName>Rioting Mob</UnitName>
                        <UnitGroupingType>UnitGroupingType_Group</UnitGroupingType>
                        <Level>1</Level>
                    </UnitInstance>
                    <UnitInstance>
                        <UnitType>Unit_Peasant_Amarian</UnitType>
                        <UnitName>Rioting Mob</UnitName>
                        <UnitGroupingType>UnitGroupingType_Group</UnitGroupingType>
                        <Level>1</Level>
                    </UnitInstance>
                    <UnitInstance>
                        <UnitType>Unit_Peasant_Tarth</UnitType>
                        <UnitName>Rioting Mob</UnitName>
                        <UnitGroupingType>UnitGroupingType_Group</UnitGroupingType>
                        <Level>1</Level>
                    </UnitInstance>
                    <UnitInstance>
                        <UnitType>Unit_Peasant_Tarth</UnitType>
                        <UnitName>Rioting Mob</UnitName>
                        <UnitGroupingType>UnitGroupingType_Group</UnitGroupingType>
                        <Level>1</Level>
                    </UnitInstance>
                    <UnitInstance>
                        <UnitType>Unit_Peasant_Tarth</UnitType>
                        <UnitName>Rioting Mob</UnitName>
                        <UnitGroupingType>UnitGroupingType_Group</UnitGroupingType>
                        <Level>1</Level>
                    </UnitInstance>
                </Encounter>

The fix is to match up the reference in the coreUnits.xml file.

In Quest_Slavers, there were a few errors that should be fixed... here is the list of them

        <QuestObjectiveDef>
            <ObjectiveID>0</ObjectiveID>
            <NextObjectiveID>1</NextObjectiveID>
              ...
              <QuestChoiceDef>
                <Description>I'll return later.</Description>
                <NextObjectiveID>0</NextObjectiveID>
            </QuestChoiceDef>
        </QuestObjectiveDef>

change the quest objective to go to 0.

<QuestObjectiveDef>
            <ObjectiveID>3</ObjectiveID>
            <NextObjectiveID>4</NextObjectiveID>
             ...
            <QuestChoiceDef>
                <Description>I'll return later.</Description>
                <NextObjectiveID>0</NextObjectiveID>
            </QuestChoiceDef>
        </QuestObjectiveDef>

change the quest objective to go to 0. These two changes combined prevent the quest Infinite-loop problem.

The other major error in the quest comes on one of the conditions.

<QuestObjectiveDef>
            <ObjectiveID>5</ObjectiveID>
            <NextObjectiveID>6</NextObjectiveID>
            <Description>The other freed slaves are moving off on their own.</Description>
            <Treasure>
                <GameModifier>
                    <ModType>Map</ModType>
                    <Attribute>CreateGoodieHut</Attribute>
                    <StrVal>Family Farm</StrVal>
                    <Unitclass>GH_Quest_RuinedHouse</Unitclass>
                    <Radius>3</Radius>
                </GameModifier>
            </Treasure>
            <Treasure>
                <GameModifier>
                    <ModType>Unit</ModType>
                    <Attribute>UnitJoinArmy</Attribute>
                    <StrVal>Unit_Quest_Farmgirl</StrVal>
                    <Unitclass>Unit</Unitclass>
                </GameModifier>
            </Treasure>
            <QuestConditionDef>
                <Objective>
                    <Icon>Mana_32.png</Icon>
                    <Text>Escort the girl home.</Text>
                    <IsOptional>0</IsOptional>
                </Objective>
                <Class>Success</Class>
                <Type>ClearGoodieHut</Type>
                <TextData>GH_Quest_RuinedHouse</TextData>
                <MoreTextData>Unit_Quest_Farmgirl</MoreTextData>
                <Flag>DestroyUnit</Flag>
                <Flag>UnitMustBeEscorted</Flag>
                <Flag>RevealTarget</Flag>
                <CompletionText>The old farmer father thanks you for returning his granddaughter.</CompletionText>
            </QuestConditionDef>
            <QuestConditionDef>
                <Objective>
                    <Icon>Mana_32.png</Icon>
                    <Text>Protect the girl from harm.</Text>
                    <IsOptional>0</IsOptional>
                </Objective>
                <Class>Failure</Class>
                <Type>UnitKilled</Type>
                <Faction>Player</Faction>
                <TextData>Unit_Quest_Farmgirl</TextData>
                <NumericData>1</NumericData>
                <CompletionText>You failed to protect the girl and she died a most gruesome death.  Rescued from one fate only to find a worse.</CompletionText>
            </QuestConditionDef>
            <QuestConditionDef>
                <Objective>
                    <Icon>Mana_32.png</Icon>
                    <Text>Don't send the girl home alone.</Text>
                    <IsOptional>0</IsOptional>
                </Objective>
                <Class>Failure</Class>
                <Type>ClearGoodieHut</Type>
                <TextData>GH_Quest_RuinedHouse</TextData>
                <MoreTextData>Unit_Quest_Farmgirl</MoreTextData>
                <Flag>DestroyUnit</Flag>
                <Flag>UnitUnescorted</Flag>
                <CompletionText>While he's thankful she's safe at home again, your heroism is in question after sending her off by herself.</CompletionText>
            </QuestConditionDef>
        </QuestObjectiveDef>

The change here is to switch <MoreTextData> to <TextData> otherwise this poor farmgirl could die and the quest will never finish (successfully or not-successfully)

These errors were all found with my quest editor, so there may still be other errors that I haven't checked for. But this will make all these quests function properly.