Be careful if rolling back.
Try and save the VEPro projects or Metaframes independently of Logic if you can. Give those saves unique names so you know which version of VEPro saved them successfully. If you can go back to a working version of your Logic project, then save out the VEPro projects (with unique names, i say again) THEN roll back (ie re-install an earlier VEPro) and see if they open.
Try and keep all your options open by saving everything you can think of!
I had a big issue a while back where a certain (beta) version of VEPro was not backwards compatible. it was a nightmare that unfolded and unfolded project by project.
When you roll back (if you decide to) use the VEPro uninstaller (inside the application folder) first. Then re-install the version you want. Do it on all machines everywhere. Save you install packages somewhere safe too (as VSL website does not necessarily archive all versions, al least not as far as I know).
It's good you can go back to early Logic versions. That will be your life saver.
Good Luck.
PS If an earlier version of your Logic project has the right sounds (but out of date compositional development) open that older project, after rolling back VEPro. Then preserve the VEPro instance and save that outside of Logic. Then, load your current Logic project, (the opreserved instance will stay up) and re-connect the VEPro plugin to the saved out VEPro project. Do NOT load plugin data from the later Logic project into VEPro. It should work. But as I say - backup up everything so you can go back to where you were (even if that point in time is not working).