They are the same commands placed in the hotkey. Your original post had it correct.
For English (shortcut Ctrl+1):
gsettings set org.gnome.desktop.input-sources current 0
For Russian (shortcut Ctrl+2):
gsettings set org.gnome.desktop.input-sources current 1
For Ukraine (shortcut Ctrl+3):
gsettings set org.gnome.desktop.input-sources current 2
Unlike my picture of dconf Editor above, you should see your language settings listed under sources. My picture has no values to switch to.