The key bug in TUCQ happened because Boingo's code had issues with duplicate Actor names, and he needed to add LOCKDEFS.
One thing that's very important for modders to remember is that all of the actors (for every zdoom supported game, Strife, Doom, Heretic, Hexen, and Chex) are loaded by the engine, regardless of which IWAD you're using, and the engine doesn't know what to do when you create an actor with the exact same name as one that's already defined.
What he has in the latest release (this won't work, BlueCard is already defined in Doom
ACTOR BlueCard : DoomKey 5
Inventory.PickupMessage "Picked up a blue key."
BKEY A 10
BKEY B 10 Bright
What he needed to do:
ACTOR TUCQBlueCard : ChexBlueCard 5
Inventory.PickupMessage "Picked up a blue key"
Unfortunately at this point he probably needs to go through and check all of his actor names, to make sure that none of them conflict with any IWAD's actors; I ran into the exact same problem with Chex Pack early on.
I spent a bit of time helping Boingo out with this in IRC, hopefully he'll get this resolved soon.