The manual says the older styles will play on the Ty3 but that if you save them in, or copy/paste them within Ty3 they are converted to the Ty3 format.
When Ty2 came out the custom voices were a different format from those produced on Ty1 and conversion software was supplied (no hassle to use).
It's not clear whether Ty3 uses yet another format, but if it does we can IMO expect the CV's to be compatible via conversion if necessary.