The funny thing is if you do something wrong the only people that will say anything will be other foreigners. So just ignore them. LOL!
I am sure the Japanese people there will be patient with you and want to practice their English on you.
We have some different experiences - While Doshu was instructing, I made the mistake of taking out my little towel and mopping my brow. After the instruction was over and before we started again one of the very senior Japanese in the room came over and "suggested" in a quiet but very direct voice, in English, that I not do that while Doshu teaching.
If you're going to mop your brow, do so after the instruction and before re-starting practice - it's a short window.
But yes, have fun training