It seems you have discovered two bugs in the Upcoming events block - well done!
Regarding the untranslated string lessoneventopens, the best solution would be for you to contribute the translation to the Russian language pack here: https://lang.moodle.org/local/amos/view.php?t=1597846365&v=l&l=ru&c=lesson&s&d=lessoneventopens You'll need to create an account on the Translation site if you don't have one already.
As for the string containing 'closes', I tried experimenting with the Upcoming events block and switching languages and found that the words often didn't display in the correct language. I found an old report of a similar problem, MDL-18589, which was closed due to inactivity. Thus, I'd encourage you to create a new issue so that developers can investigate and fix it.