* If memory serves me right, the demo does not allow you to save .jas documents, be they new or edited old stuff. If that assumption is correct (and I hope that Frank or others will chime in) you can not really "corrupt" any existing models with a current trial version.
* C3D V5 is, of course, a bit medieval by now. Bear in mind that quite a bit of additional trickery needs to be researched and experimented with.
* I believe that Frank has an archive of old C3D versions for sundry testing purposes, so he should be able to help with any queries.