Hello,
I had exactly the same issue and I wanted to try another time to check but thanks to you I don't have to ^^
What I did:
In "Language support", I added English that was strangely missing, in the list I put it first and and remove my language, I clicked "Apply system wide" then I logged out.
Back to my session, I used "language support" to add my language and placed it first, again "apply system wide" and logged out again.
Then my session was properly showing my language.
This is a huge accessibility issue, not being able to read the text screen.
In Ubuntu 24.04 languages are poorly treated to my opinion.
Does anyone know where to report this issue?