First, did you tell Apple that their update broke your program?
Second, Yosemite sometimes has problems, often related to "default" permissions needing to be changed
-one person's solution https://forums.adobe.com/thread/1689788
Third, old rule... "if it isn't broken, don't fix it" !!!
That's very strange, Rod. I don't see how changing the operating system would have any effect on the version of the program.
I am strictly an Elements User and problems with the same symptoms can (often do) have different causes. But, you mention of
"The project is not compatible with current version of Premiere Elements" coupled with "DVD menus" brought back a 2011 flash back
of a Premiere Elements 9.0 Windows issue.
As a just in case, please check it out and determine if any of it applies to your situation in spite of the fact that on the surface your issue
is presenting a going from one Mac operating system to another.
In another more recent instance this type of error message pointed to disc menus...
Have you checked the integrity of the related Premiere Elements 10 computer saved disc menu themes in the change from one Mac operating system to the other?
We will be looking forward to your progress.