On occasion I would run into that I would get the ""incorrect version is installed. Rerun workstation set up"" message. Rerunning workstation set up for that version of MAS (usually the lower one) resolved it.
Reread your post, are you actuall installing Crystal on the workstation or just having issues printing Crystal reports? If so, just go with 11.5. I've never encountered an issue using a v11.5 level form in v4.3.