Another thing,
On Ubuntu 18.04.1 (Bionic) that I run, I just made 2 changes in the Settings, option Region & Language, from English(United States) to English(Canada) in the Language entry field as well as in the Formats entry field and the command "echo $LANG ⎥cut -c1,2,4,5" displays "enCA".
When I changed the both these settings to English (United Kingdom), the command "echo $LANG ⎥cut -c1,2,4,5" displays "enGB".
While I don't respond exactly to your request for the number value of the language used yet, this way should solve your problem, willn't it?
Cheers.
Fifi