Most importantly (even though not answering your question): backup your files!
The biggest danger will be that when you are saving an older file in a newer version (by mistake or on purpose), that you will not be able any longer to open it in the older version. It is probably best to not only have multiple versions of Xojo installed, but having a versioned backup hierarchy of your most precious files. Especially with binary files there is little chance you will be able to get your work back in the worst case.
Hi , can’t you setup and work on docker containers ? Then you have always a defined environment.
Or setup multiple VMS. In old times I was using different hard disks… .
Another option is a tool like gclient ( depot tools from chromium project). Everything is defined in a deps file, which is also checked in. And the starting point is always a glient sync … .