"Ble mae'r ysgol cyfrwng Cymraeg?"

Translation: Where is the Welsh-medium school?

[Niwlog]

I was curious about the lack of mutation here after ysgol and found quite a mixture of web uses. Some mutate both, some neither, and others one or the other of the two. Can someone clarify?

[KierenMcCormack]

Would it be correct in saying "Where is the Welsh school?", or would saying medium be necessary?

[mizinamo]

There's the word "cyfrwng" in the original sentence which probably ought to be translated.

[EllisVaughan]

And we almost always say "Welsh medium" when referring to schools.