@Schnark How do you suggest we handle this? Letting messages stretch the box is a bad practice because it can cause issues on small screen sizes, it can cause interface inconsistencies, and it can encourage translators to make messages even longer. Truncating messages seems like the best of a load of bad options to me. I'm willing to hear alternatives though. :-)

Well, I don't really know a good solution, either.
Actually, this can be considered as partially fixed. When I reported this, I wrote "The full title isn't even shown when hovering over the truncated title.", this is the case now, so you can see the full title now by hovering.
One other idea would be to limit the width of the buttons and truncate their labels, too, if they are too long, which will reserve more space for the title.

‘Handling without truncating’ is a lot more complicated than you’d think. If you merged my task into your larger task, @Schnark, I think you should’ve cited the proposed solutions from it (increasing the width of edit saving dialog and any other).

I agree, the modal dialog should be wider, some languages do have problems to fit in there