a loch (or a lochan, I’m not fussy), whatever, a body of water enclosed by land. Okay.
I obviously know that the Scottish word for Lake is loch. If I was referring to a lake in Scotland, I’d call it Loch whatever, like I did above. That does not mean that it isn’t a lake too.
When I go to France, I don’t say ‘I’m going to France to swim in a lac’? If I go to China, I wouldn’t say I’m going to China to swim in a ?. It would be pretentious. Why get so het up that I don’t switch languages mid sentence in this particular case?
Also, sort of relating to this, in Aviemore last time, I had terrible trouble describing where I’d been to a bunch of elderly locals, as I only knew the Scottish name of mountains off the map, whereas they seemed to mainly use the English translated name for the smaller hills, and didn’t have any clue of the Scottish name. You can’t win!