I play recorders and flute (occasionally), starting with recorders, which come in C or F. Flutes come in G and D. Eventually I realized that although I was unaware of it, the weight of the instrument was telling my brain how to finger it.

My brain was thinking, "This instrument is heavy, therefore it's an alto in F." But no, it was actually a flute in D.

Therefore, Dave, I think you are doing the right and logical thing. Accordion and concertina feel different and weigh different amounts, and it's a good idea to assign different versions to different instruments.