I already thought it'd be fixed now since the login went flawlessly. However, it still took a reload to get to this typing window alongside with other similar issues.
[Edit] Posting the above worked like a charm but ppening the "modify" window took a couple of attempts.
[Edit2] Posting the modified post worked, getting here again wasn't as fiddly as at the first time. This system seems to like repeated actions.
[Edit3] Then again, posting Edit2 required reloading so there's still something fishy.