I think what's crashing your game is probably the .cat file(s) of whatever costume(s) you're trying to import.
DOA2U's .cat files are encrypted, while DOAO's aren't, and the game won't know what to do with an unencrypted .cat file.
You'll need the encrypted .cat file of the original costume that your mod costume is based on. E.g. if you have a costume based on kte00, you'll need DOA2U's kte00.cat as the .cat file.
DOA2U's .cat files are encrypted, while DOAO's aren't, and the game won't know what to do with an unencrypted .cat file.
You'll need the encrypted .cat file of the original costume that your mod costume is based on. E.g. if you have a costume based on kte00, you'll need DOA2U's kte00.cat as the .cat file.