Looks good, merged. Thank you 
My Caliguvara Preset has a shell script widget integrated doing basically the same thing. The only hiccup compared to @kovpas' solution is, that you'll have to add manually the languages you want to be able to see displayed, where your widget just needs another tool being installed. Advantage, you can change the language input by tapping the icon. Maybe this could be an idea for version 1.1 
It doesn't work on Catalina. Installed the binary, imported the widget, checked the settings, nothing shows up on the touch bar.