EssentialsX version (run /essentials):
Essentials 2.0.1-b579
Server software (run /version):
CraftBukkit version git-Spigot-9b8bba4-bdcc7c7 (MC: 1.12.2) (Implementing API version 1.12.2-R0.1-SNAPSHOT)
Server (logs/latest.log):
Pastebin
EssentialsX config (plugins/Essentials/config.yml):
Pastebin
Details:
Pictures say more than a thousand words: Imgur

I'm gonna assume that {WORLDNAMESHORT} is not working?

It's supposed to be {SHORTWORLDNAME} as per http://wiki.ess3.net/wiki/Chat_Formatting

As @LaxWasHere said, the token for shortened world name is {SHORTWORLDNAME}.