John,
the official moinmoin repos have changed to
  https://github.com/moinwiki/moin-1.9
so the files I've referred to were

https://github.com/moinwiki/moin-1.9/blob/master/docs/resetpw/wikiconfig-note-snippet.txt

and 
https://github.com/moinwiki/moin-1.9/blob/master/MoinMoin/theme/modernized.py#L90


The roundup-theme-fix-20190829-1.diff fixed that the "important" box
is shown, if it is activated in case of wiki maintenance or other important
messages to all wiki readers. Only an admin can trigger it, so
we can assume it is applied if Thomas accepted it. He could use it to give a message
if we invalidated all passwords or something similiar.
An only in this case it would overlap.

You could test the overlapping independently by setting up a moinmoin instance
with the current roundup style. As it is a rare situation to show the info box,
it shouldn't have a high prio in my view.

The other points were about improving the theme overall and adapting it to the current
themes:

* The icons used are a bit outfashioned as modernized has icons which are better.
* Layout and icons can be improved overall like with the memodump.
https://moinmo.in/ThemeMarket/memodump

My suggestion: close this issue for the import box style fix and create a new one for a more general style improvement.