I remember similar problems with Lands of Serenity. I started it in 1.90 originally, before any of the 1.92 betas came out. When Beta 163 came out, I switched over immediately, and it was great. Only problem was a lot of enemies got jumbled up. There were an awful lot of Digdogger kids. (? ? ? ?)
It was just a matter of editing that stuff back to the correct values, and all was great. Well, except for the bug in the last level where you couldn't walk onto a stairway, thereby breaking the last level. >.>
So I updated it to 2.10, and fixed the bug, and a whole heap of other bugs popped up, too numerous to list.
This seems to be a risk that you have to take whenever you update a quest to a new version. Some people don't have many bugs at all, and some have to wade through a whole load of them.