Some related fixes have already been implemented (ironically submitted by my sister). But…
Right now, if all the assignments are due at the same time in the assignments widget, it seems to have no rhyme or reason to how they are sorted. I would suggest that the easiest fallback would be a secondary sort by title alphabetically. My current fix is to go in and set the order by changing due dates by a minute or two in each direction to get them to sort right.
While you can sort the assignments in the widget while you're selecting them, that sort order has no impact on the display of the assignments in the widget. That would be a totally fine alternative: Seth sorted the assignments by name in the widget, so let's fall back on a sort by name if there is no other criteria to order them!).
The display in the widget is… poor. Ideally, the widget would show at least some of the actual assignment description (think of it like "up to the break" in a blog post) in the widget, rather than the fairly useless assignment type metadata. It may not be 100% useless, but it takes up far more space than its worth, while concealing actual student-focused information.
Forget my second screenshot -- I just remembered that I was fighting with another annoying configuration so the due dates are really in order (in my head they were all 8/22, but obviously that's not the case)
it gets worse
See screenshot