It's correct that we now check for presence of a certain Denise/Lisa ID in order to make a difference between A600 and A1200 accelerators (that was the routine that was buggy before, this chipset-recognition is new in V1.7).
However, ACAtune is meant for computers with an accelerator. An emulator cannot have any ACA card. I find it a bit far-fetched that a piece of software that is specifically made for a special hardware is expected to work on an emulator which does NOT emulate any of the ACA accelerators.
Toni Wilen has the full documentation of the ACA620, which also includes part of the ACA card recognition. He may be able to fix UAE in a way that it reports "no accelerator found". I refuse to add complexity to ACAtune just for compatibility with a weird case. It's like adapting a car tire for use on a bicycle.