https://bugs.winehq.org/show_bug.cgi?id=43910
--- Comment #41 from Storm Engineer hewanci@gmail.com --- UPDATE!
After downgrading nvidia drivers solved my graphics error, I have noticed that most things in Battle.net work now.
I assume this is the side effect of my creating a clean prefix while trying to solve said graphics error.
The only things that still crash Battle.net Helper.exe: - Overwatch League tab - News for these games: Diablo 3, HotS, Overwatch.*
*News for everything else, including the News tab itself do work, curiously.