If I were to design this system, I'd make the language picker very prominent and have a very clear explanation saying to make sure both parties have the same language selected before comparing the words.

Alternatively, the party whose code is being confirmed would just select the language, and the other party's UI could automatically update to show the code in the chosen language. The first party would still have to pick a language both people understand but (as long as both parties have a working internet connection) there wouldn't be a sync issue.

I would just use numbers.