I've updated first post of this topic to make current actions more clear.
BTW: I remember the info I've found on official Russian forum and it's bad for us: cracked game can be the reason to have some quests impossible to finish. :(
Umm, you do know that you cannot believe everything you read on Russian or any Internet forums for that matter, right? How credible is this information exactly that it should be accepted as fact?
The way I see this is there were two issues found with this game and they have been corrected. This is good news. The problems were solved. Why does it matter how they were solved? GOG isn't out to screw you, you know? You made them aware of a problem (thank you) and they saw to fixing it. Time to go play!
As for the possibility of other hidden bugs in this or any other game I can make you a promise there. Yes, there are bugs. There are bugs in virtually all software. Having worked for many years as a Senior Software Engineer involved in Software Quality Assurance of complex systems I can tell you that software always has bugs. It is not humanly possible to effectively test for every possible scenario or path through complex code in software. Given that software projects are coded by human beings they are subject to human error. This is something you can actually depend on: that humans will make errors. Then on the PC platform there is the large issue of such a wide variety of hardware and software environments a given program attempts to run within. It isn't actually doable to test for every scenario here either.
Considering the limitations of software engineering as it exists today it is something of a miracle that so much software runs as well as it does. But to think that any given program, game, etc. does not have any issues would be to delude oneself.
So I'm sure King's Bounty has some bugs in it. Whether you ever see them however is another matter. Hopefully not. You could make a career out of analyzing this one program you know but it isn't likely to yield you fruit that makes this effort worthwhile. I applaud your initial and successful efforts at getting two issues you ran into fixed, to the benefit of us all who bought the game. However, I question further pursuit of bugs you haven't even encountered yourself when you could instead be playing the game and having some fun for yourself.
I have a funny feeling that analyzing this particular program has become something of a fun game unto itself for you. In that case I guess I should just encourage you to have fun and game on! :-)
Don't take me too seriously please because I really don't mean this to give you a hard time. I just think it is kind of funny to spend this much time worrying about this game when the problems you found were fixed and you could be doing something that is presumably more fun.