From the 1960s on the west of Ireland was aflock with Germans. It started, I think, from an article in a German news magazine about the safest places to live after a nuclear war, and then there was Heinrich Boll's Irisches Tagebuch (Irish Journal), which pictured our country as a land of dreamy, sweetly innocent peasants driving donkey-carts. German idealists took this hook line and sinker, and proceeded to visit Ireland annually, with many moving in.
The tourists were perhaps a little less popular than those from other countries, because of a perception that they took more than they gave - even the cycle tourists often thriftily brought their own food with them, and stayed in hostels or campsites rather than giving business to local B&Bs and shops.
So any sharp references to "the Germans" in the play are probably the Donegal people feeling a certain reserve about being treated like a human zoo in a beautiful landscape by people who may not wish to form any real exchange.
(All this has largely changed with the tourists coming back year and year and growing older and richer - in their fifties and sixties they now tend to be sensible and stay in B&Bs and buy from local shops. And those who have moved in largely went native; I remember visiting a friend in west Cork some years ago who had been waiting three months for a local German carpenter to come and mend the window.)