FYI, I just updated our wiki  to the latest stable version of MediaWiki 1.32.0.
The major benefit is, that finally the Extension:Math works flawlessly by using the Wikipedia API for rendering.
One drawback is, that I chose to drop two old skins (Cologne_blue  and Modern ), that are no longer bundled with the default installation. If someone really wants those skins, I can enable them again.
For more information on the wiki installation see  and  and feel free to report any issues you face since the wiki update.