I found quite a weird bug (or easter egg?), when accessing the lotr forges:
Only in slot 3, instead of putting the items there, it opens NEI and shows me some recipes. It depends on where I click with the mouse pointer in the slot. Lower left -> works, central -> bug. The items drop on the ground in front of the forge and can be picked up there. It seems, that I access some invisible slot that is somehow off compared to the GUI.
Not sure, what Mod is responsible for it, but I guess, it might be your addon.
Edit: I could replicate it. NEI has a feature I just noticed now which allows you to view all recipes of a recipe handler by clicking at a specified location on the GUI ("transfer rect"). I forgot to disable the default transfer rect for the alloy forges which shows all recipes of the default craftingtable. As I discovered this features, I plann to add transfer rects for the handlers of the addon (but they'll be placed correctly).
The addon hides some "technical" blocks - and because I've hidden this block (because it was a technical block some updates ago) and forgot to remove this with the update where the dwarven door were improved, you can't find the "normal" dwarven door with NEI. Thanks for reporting! The fix is easy, but unfortunately I currently don't have the possibility to work on the addon. I'll release a patch in two weeks.