Hi Swissman,
There are other Ty2 owners around. Maybe they agree there's a problem but don't have a 100% technical solution! The more complex the change is from the existing to a new registration the worse it can get. Try going from full keyboard piano & layered strings to split KB solo instrument for instance.
The only way seems to be to avoid known "bad" combinations or at least minimise the effects by choice of voice or anticipate by creating momentary voices off for the change. In the latter case don't forget the sustain pedal and any left hand voice with left hold on!

Possibly the reason using OTS in preference to registrations was mentioned above is that you have an option with OTS. Go to Function/Style Setting and set the OTS link timing to what you prefer - Real time or Next Bar.

But there doesn't appear to be a similar
option for regs.
John