We do not have enough info about the version string for the FT-4 or FT-65. If the string is a mismatch, I would like to ask the user if it is OK to proceed. Is this possible?
No, not possible by design. Even still, 90% of the users will have no idea whether to proceed or not, so they will say "yes" and if something goes south they'll be pissed.
The best thing to do in this case is to log heavily in your driver, and try to collect a bunch of data. Ask on the ML for people to try cloning with the driver and report back what radio they have, whether it worked, and attach their debug log to the bug for analysis.
I can tell you that, from experience, Yaesu radios are not at all good at sanitizing what you send them. I have soft-bricked Yaesus before having sent them something that causes the internal micro to get unhappy. Since most that I have encountered do not actually fully clear their memory during a master reset, they're often not recoverable like that. Since I had hands on the radio I was able to figure out what was set wrong specifically from the clone traces I had done, craft a stream to right it, and get the radio back. You want to be extra careful doing that for someone remotely and be sure that if you brick their radio in any way, they'll be extremely unhappy with you.
--Dan