A triple-post update:
Okay, I've switched back to WINE-Dev: In the end Proton incurred crashes, if I recall correctly.
And I thought for a while that I could just play without the cutscenes, or at least just reading the text that accompanies them...
... However, I made it past the tall shield-bearing (mini-?)boss, broke a yellow object, and so initiated a cutscene... which doesn't seem to end. After some initial sounds, it just sits there, repeating a quiet sound on loop. Perhaps more importantly, it doesn't seem to respond to input (including holding "escape" to skip).
As a result, and presuming that whatever I gain from the yellow object is important, I seem to be stuck. :/
(Which is only more frustrating as I had trouble with another game that I bought just recently, Hands of Necromancy II, leaving me with two games just bought that I can't really play. :/ )