XeNTaX

Actually, pretty much every data file for mu online uses the "bmd" format, each with different type of encryption.

There are some tools, but probably not many people bothered to look into it after tools were available.

i doubt they are different encryption ma bee they are but i doubt it.
you could just attach a debugger and step through the program that opens the files to get the encryption.
but these models look really low quality so i am not interested in it.