Thanks Guessed,

what exactly did you pass on if the user selected a language in the Userform? The LanguageID, the Caption Labels? I thought about a workaround in which I add "Figure" and "Table" as custom caption labels and refer to them, instead of Caption:=wdCaptionFigure.

Unfortunately my situation got weirder.
It seems like the captions get properly labeled in English until the point when I insert the TableOfFigures. At this point all the captions in the document change their language.
And this appears to happen randomly (which makes debugging a nightmare).
I did change the style of TableOfFigures to English hoping that this solves the problem but this behaviour is very strange.
I also thought about changing Normal.dotm to see if this property gets pulled from there for some reason.

More details on your solution (which I would include without the Userform) are highly apprechiated!

Tobias