The rounded edges/sides of highlights have got to go. It boggles my mind that this doesn't seem to be more of an issue to others.

If you highlight a portion of text, the left and right sides of the highlight are shaped such that it both visually and functionally spills over onto the adjacent [un-highlighted] text.

Because of this, the adjacent text is extremely difficult to select; 9/10 times, you end up selecting the highlight element. The resulting markup just looks cartoonish as well.

I’m guessing that implementing a rounded shape for all highlight objects in acrobat, is far more difficult than simply having a rectangular one. So someone put in some effort into this for some reason.

Keep it simple; I know it’s hard.