As you might not know, the engine is evolving constantly. The lite-C and C-Script languages are slightly different; nevertheless, any A6 project that has an updated C-Script syntax will run fine with A7. What do I mean by "updated C-Script syntax"? Well, "time" was replaced with "time_step" and so on (A7 wasn't out at that moment, so these are C-script updates). Finally, there's a guide that tells you how to convert your code from C-Script to lite-C in the Aum.

I can tell you for sure that projects that were created about 4 years ago (Aum45, etc) were designed for A4, A5 and so on. Newer projects (think Aum60 or newer) should run fine with A7; if you have problems with one of the Aum projects that's newer than (let's say) Aum60 and doesn't run fine with A7 post a screenshot that shows the error messages here.