Russian translation is pretty bad.

Is there any way I can contribute to make the translation better?

Assuming you're talking about the legacy 1.x version: sure. You can fork the repository, and update the src/main/resources/assets/chesttracker/lang/ru_ru.json file in the legacy-1.x branch which contains the Russian translation; the English translations are in en_us.json. Once you're done, submit a pull request and I'll push a new release. If you're not comfortable with making a PR, feel free to just upload the updated ru_ru.json file on this issue and I'll add it.

PR in #114