I went to create the new BB code and it already existed. The replacement string was slightly different. I then updated that with what you put in your install doc and it fixed it. You must have the creation of the BB code in your xml which all you would need to do is update that.
When i click the approve, i get as you described above,
please_complete_required_fields
One thing you might want to remove that avatar.php out of the admncp folder in your file. I dont think that was supposed to be there unless you intended to impose a file code change, which could be a problem on the wide range of versions since that file already exists in the admincp folder.
I dont see where the usergroup change is. My intention is to not allow normal moderators but do allow super moderatiors to manage the adding of rank tags in the ModCP. Is it somewhere im not finding it?
Otherwise thanks for the updates so far. Im sure the bugs will be worked out quickly since you only have a small few.