Thread:User talk:CodeCat/Language codes in templates

Hello you. I haven't concerned myself with templates at all but I do sometimes find that they get longer and unwieldier over time; therefore I was pleased to see the recent news that we can use "en" etc. as first parameter. However: why do some templates support this while others don't? (I think perhaps "cx" and "sense" don't, off the top of my head.) How can one tell without checking source code? Should they all, one day, support the language-first format?