Hi, indeed it's not possible, that addon doesn't have this feature.

You have to use different Form component. There are FREE and PRO available in JED, so you have choice. Then if that component has module, it can be used inside the Module addon (SPPB)

Convert Forms, RSForms or JSN UniForm. Are these third-party extensions or are they in sppb?

Of course, third-party extensions. Personally I recommend Convert Forms (tassos.gr).

in Convert Forms, in my opinion, there is no russifier (translation into Russian)

Maybe RU community have it, like always. And check also here:

https://www.transifex.com/tassosgr/convert-forms/

That's all I can help.