I'm afraid this depends of your browser.
So you'd better be trying to look for "how to add X language to Y browser" on a search engine like Google's for example.
Otherwise, normally you should, when using the "Speak text" action add the "ru-RU" or "pl-PL" (be sure to confirm exactly what are the supposed tags to use, those are simple guesses) language tags to the "Language" field.