Thanks for listing those things. This is the point where I would have asked you to create a bug report but someone did that with most of those things here: https://github.com/selfthinker/dokuwiki_plugin_fontface/issues/24
Maybe add the additional info there.
I rarely check stuff on GitHub because I only work on DokuWiki once in a blue moon. But I might put some time in during the Christmas period and work on some plugins.
glreschke I cannot prove that the plugin IS compatible with the actual DW version.
If it is working for you and you have the current DokuWiki version that is proof that it is working. If it is not working for someone else wouldn't mean it isn't working at all.
You can update the wiki page and change the compatibility information.