Despite trying everything short of buying a new SSD, I have not been able to reverse course as you say . I have tried so many things to get RM working its just not even slightly funny any more. To be fair to RootsMagic, [...] subscriptions are **** expensive). Oh well, I guess I just have to hope that RM are working on a native Mac version and it won't be much longer.
I have had similar experiences. On one host I was able to reinstall onto HFS+ and the problem disappeared. On the other host, I found that after installing a demo version of the standalone Crossover product and reinstalling RootsMagic into it I was able to get around the immediate crashing error. So I now have a "working" RM7 though it hangs on FS interaction every 20 to 60 minutes.
It does appear that there is an issue affect 32 bit programs running on CrossOver on Macs with High Sierra and the appfs filesystem. Now I have uncompromising perspective about bugs like this and responsibility.
RootsMagic runs on Crossover on OS/X
RootsMagic didn't create the bug but it is still a RootsMagic bug, unless RootsMagic were to say "we don't support High Sierra" The bug could possibly be fixed by any of Apple, Crossover or RootsMagic.