Doesn't really make a great case. I obviously recognise both the union jack and American flag as "English", and nobody would expect it to mean Welsh. Also there are approximately no people that speak Welsh and not English.

It's one of those "yes technically you're right, but actually it still works really well in practice so sod off" things. It's like saying tomatoes should be in the fruit aisle. No thanks. Sometimes utility is more important than anal correctness.