As for Story/Quest -- it happened once, and later I also saw "AI". Guess you are right, it is because of switching languages and should not reproduce any more.
I can't find "Special thanks etc." in ru.po, and without translating it I can not properly translate "you" in this context. I have added the most probable version, but could you please give me a screenshot of the result also?
And here are the changes by this moment, you can update the beta version.
Also could you please provide a screenshot of the newsletter window after update so that I can check my corrections?
Upd: another untranslated string, header for the letter from G3 about challenges ("Since G3 has become the biggest meetup...")