Translation to Russian?

another Q’s:
How to translate “Submit” button at front end? when posting?

How to translate interface buttons?

In the last version of the plugin, you can edit it in the settings of that post form:
https://prnt.sc/10tnoti

Yes, i found that one.
And all other buttons of the editor and labels?

You need to translate something manually. You can use this plugin https://www.ads-software.com/plugins/loco-translate/