I did some more testing with exports and it seems the changes the dnd 5e 2.1.5 were trivial. Even exports made by v1.1.1 of the converter work, even though they throw some errors in the console.
I've updated the FoundryVTT template file the application uses, this seemed to have fixed the errors. I'll do some more testing before releasing v1.1.2, which should fix both issues mentioned here.