Last I read, they had only one developer still left from those days, an art director. That said, I understand Chris Metzen came back, so maybe two. In any case, getting merged with Activision, with Kotick at the top, will do that to you. Online only has made Diablo 3 and 4 distinctly worse than they could have been.
ANYWAY, as to the OP's problem, Applecheeks' thread regarding use of ProtonUp-Qt may help them get the runners suggested in that workaround link.