I’ve had Celiac for 16 years now. It still hasn’t gotten any easier to explain things about what I can and can’t eat in foreign languages. Perhaps this has to do with the fact that I only speak English (if only I picked up other languages easily).
However, before my trip to Switzerland for curling (which is 5 years ago now, and seems like it was yesterday), my mom found this website. The creator has posted cards explaining what Celiac is and what can and can’t be eaten. This was amazingly useful even when the person I was talking to spoke rather fluent English. I forget how you don’t learn a lot of technical type language when learning a new language.
I’ve yet to need any language which I can’t find on the cards. I usually print off multiple copies as it has gone best when I can give my server a card and not have to worry about getting it back. That way they can bring it back to the kitchen and not be worried about ruining it. This results in awesome food with very little fear of ending up sick.