How do you add large rooms to themede dunegons?
The entry keeps removing itselfs when I try to add themeLarge4

Large rooms are only available in tier 2 dungeons (for now), sorry. There is a lot of hardcoded logic in place to make them work.

Would allowing rooms types to be allowed to be omitted help? [Fourways, Threeways, Hallways, Corners. and Large]

Entrances and Dead ends would remain mandatory but if the room entry is blank then those types of room would not be used in generating the dungeon, it would open large rooms for other dungeons while not effecting the default dungeons since they don't have a large room entry by default

That's a good idea. (Also currently not supported.) I expect that if the list of hallways is left blank, the game will crash.

You might be interested in this page: https://github.com/AllenSeitz/DimDungeons/wiki/Building-Custom-Rooms#dimensional-dungeons-hacks