I have only one user on my pc, with all administrator privileges.
Beside of that places that i tried before, windows found export.lua files only in the "recently used" folders that leads me to those that i already tried.
While i was writing this answer, accidentally i found, thanks to your suggestion about missions, correct folder of DCS. Because of my Windows language, my SavedGames folder is called a bit differently (with other meaning) and thanks to some other game who presumably created catalog called exactly "SavedGames" i was mislead to think that this was the correct one :/
Thanks for suggestions. Now everything works as it should.