(Well known fact) I’m living in Slovenia and have no Welsh speakers at work but when I enter the office I many time greet them with “Bore da.” Now they all know I’m learning Welsh and I don’t get puzzled looks back just some friendly smiles and continuing this way I might get “Bore da” in return one day, who knows.
The story from when I was in Caerdydd you can read here. The “story” describes exactly such situations.