Hmm. In principle, the old updates work quite well.I used to play this game, but I stopped keeping tabs because it was grind fest (and not an enjoyable one) and I had to start from scratch every single update. Has is gotten better in that regard? If not, is there some way to hack 100%?
I even saw a 100% save here.
But in general, I personally only played the game three times. Now all saves of version 4.0 and higher work with version 4.9. Only this is actually a temporary issue, since it is not clear what the author of the game does. It is quite possible that after a major update, which the author is currently working on, you will have to go through it again.