I try adding note for gelbooru.com/index.php?page=post&s=view&id=3472148 It is an absurdres image, maybe that's part of the issue?
I tried test-wise adding notes on gelbooru.com/index.php?page=post&s=view&id=2907036 and that works just fine, the notes transparent outline appears and when clicking it the box for adding the note/the text also appears. But no such thing for gelbooru.com/index.php?page=post&s=view&id=3472148 . Could the reason be that it's absurdres? Or what else could be the reason, since I could obviously add notes (just not for the image I want to)
(I tried adding notes when loaded with being resized, and also after loading the full sized image, but both fail)

Works fine for me. The notes are added, so you can use them and translate the image, if you still feel like it. If something doesn't work, try it with a different browser. That's just a way to test whether something is wrong with yours.

What browser are you using, any extensions or greasemonkey scripts that are not standard?