Chrome is better in that when you edit an existing post with a spelling error in it, the red squiggly line isn’t visible but the instant you make an edit, it then appears. This makes sense. Edge doesn’t do the same and the only way to force spell check is the cut & paste the text back.
I don’t have Safari but it sounds like it has a similar problem as covered in this post:
Considering this, I don’t think it’s 100% fair to say it’s Edge’s fault. It would be fairer to say that this is one of those many edge cases in the HTML standard. If there is a workaround for Safari, should there be a workaround for Edge?
Ohh this is interesting, I’ve edited this post a couple of times and the red squiggles are there now when I edit the message - without doing anything.