When the new wrapper is released, is it intended to be a universal replacement for the current one or just intended to work on Catalina? If it is not a universal wrapper, I trust it tests the O/S version prior to trying to install. Based on what I've read, I hope it will also halt installation, if there is an existing installation of the wrapper.
Just to put a slightly different perspective on this. I use the full version of Crossover, and updated to V19, which is the 64-bit version, a month or so ago whilst still on High Sierra. RM7 worked just fine on that for me, which involves very heavy use of the Family Search interface. I have left RM running for many days, with my Mac sleeping at times, particularly overnight, but the FS interface picks up every time when I return to it. At the beginning of this week, I finally decided to update to Catalina, and RM has worked just fine since then. That suggests to me that the new wrapper should work equally well on previous versions of MacOS, not just Catalina.