I played and finished Legacy. I don't use GOG Galaxy. I have a habit of keeping mysave files before installing a game. After I finished the game, I cut and pasted save files into a different folder. Then I started the game again. I confirmed there isn't any load point under load section. But when I checked achievements section, my achievements were there meaning that they are not stored in save files. and once I uninstall the game they will be göne. So, does anyone know where are those achievements are stored?

I found it. The "prog.bwl" file in the game installation folder has the achievement info. It's not in the saved games folder as normal save files.