OK, I won't ask for a language per se, but I'll suggest to add SQL puzzles and maybe some multis with SQL interfaces.
SQL sintaxis is very important on many environments, almost any data collected on any multi-user program lies on a database. And as you know other competitive programming webs already have SQL in its porfolio.
So I think it could be a good addition to have some SQL puzzles:
* Easy Puzzle: Some simple SELECT * requests, with filter and ordering maybe.
* Medium Puzzle: Some inner joins to fetch data from multiples tables
* Challenge/Multi game: As part of input data, give the info from a database instead of stdin. I suggest that on a future Trading Card Game challenge (like HeartStone, or Magic the Gathering ) , you put cards info on a database, and users need to fetch the data from the DB instead of stdin.
MySQL (or MariaDB), PostgreSQL, and Oracle Express are available on Linux, and maybe MS SQL have the Express Edition ported to Linux too. But with only one DB engine is enough, really.
Maybe that's harder than adding another language, but I think it worth the effort, I consider SQL language essential on modern programming, reading from stding it's ok because it's simpler to detach the program from IDE and working outside it. But SQL it's a must on many developer positions.
And as a fun fact, SQL language is Touring Complete, so in theory is as powerful as bash