I just noticed that [[ https://ca.wikipedia.org/wiki/Usuari_Discussi%C3%B3:Amire80 | my user talk page in the Catalan Wikipedia ]] was converted to Flow. Thanks to whoever did it (@DannyH?).
There's an issue, however: It's in a category that has a //French// name: "Page de discussion fonctionnant avec Flow". I'm not sure where does it come from; such a message doesn't seem to appear in the Flow codebase.
And while writing this bug report I noticed that the same happened on my [[ https://he.wikipedia.org/wiki/שיחת_משתמש:Amire80 | Hebrew Wikipedia user talk page ]], too.
There must be a French category name lurking in some conversion script or configuration file, but I don't know where to look for it.