Anyone out there who knows if it is or is not possible to change the interface language of DokuWiki?
You mean every user can choose his desired language, right?
In which language is the content of your Dokuwiki written? In one language? In multiple languages? (Only pictures ;-)? I suspect your use case is something special.)
With the translation plugin (https://www.dokuwiki.org/plugin:translation
) you can set up several language areas. (Each language has its own namespace.) When a page is called in its namespace, the interface and the content language are switched both. Just as the function is on www.dokuwiki.org too.
Whether there is the possibility of a per-user configuration, I do not know. I suspect that do not exist. In a rough review of the plugins with the tags "language" and "translation" I found nothing similar.
If you do not get an answer here, it is often a sign that the desired function does not exist. But as there are currently 1203 plugins, almost nobody can claim to know them all in detail. Therefore, it is difficult to assert that something does not
What did I overlook?
Maybe you overlooked nothing.
HTH - Michael Sy.