Irish blood in me, but have some British traits too! However, I have learned over the years to be a bit more assertive when it comes to bad grub in restaurants. It's not easy but if you are discreet and kind it can work beautifully.
If something is truly awful, or not cooked well enough, or cold or whatever, when the wait staff come over and say "how is your meal", I say, hi I was just wondering if you could help me here, I just think to me the meat is tough, undercooked, cold whatever, and it just isn't what I expected when I ordered. Thanks so much, or something like that. No big hoo ha, it always works. And a big tip to the wait staff if they sort it out. I got over myself years ago, but would never be THAT attention seeking person looking for the impossible either.
Google translate is your friend when abroad in a country where you don't speak the lingo. Has saved me from some horrible meals!
But I would never ever criticise a dinner party meal that someone has gone to great trouble about. If it is not something I like, I just say "small portion for me please" and stock up on the accompaniments!
I've also learned to push into a Q abroad. When in Rome and all that.
But there are times when I won't make any comment, usually if it would embarrass those around me or even a stranger. I can't think of an example right now, but if I remember I'll let you know! We all do it if we have any emotional intelligence!