After saving all configs via /defaultsettings saveAll command and removing options.txt file, after restart mod only applies keybind settings, but lang and guy scale, as well as other options doesn't applies from mod DefaultSettings folder

This is intended behavior. If you ran those commands and delete the options.txt file afterwards, the mod will treat this as a local change of settings (as the ds_private_storage.json file knows that the options.txt file has already been created before). It won't interfere with it and thus those files will contain standard values.

If you want to ship the modpack, you must exclude the options.txt file AND the ds_private_storage.json file. To simulate that, you could locally delete both of these files. Then with the next startup the mod will set the correct settings.

OK, I would try and write to you afterwards

My bad, that's true: deleting ds_private_storage.json helps. Closing.

You're welcome :) Feel free to reopen in case you notice another issue with that particular feature.