Ok. Here's photo for better understanding.
It's not showing if the whole set is equiped and which parts are missing, what are whole set bonus.
Weirdest thing is, if I for example would change dark crystal's SetItems-Classic.grp with eternal or leviathan armors ids, it won't work either. It shows only data from ItemName-e.dat
And to further increase my headache, I can't wear cloak anymore. With any set it just says ,that you you can't wear it, because your set is incomplete...