congrats to your kill...
but a lvl 18 elite monster is not a "world boss"
World Bosses are Bosses
the have the same lvl like raid bosses
While I would tend to agree with you in most games, I found this one to be quite more challenging than most max level high end bosses from other games.
With a group of 10's-20's (mostly 12-15) and a few 20's. It was not the most easy encounter. That said, it wasn't extremely hard. He had around 191,000 hp, and during one encounter, he one shot our 23 who had 4.4k hp. It wasn't completely a tank and spank. He performed other tricks.
I would say he was the world boss of Coruscant, because for the planet of Coruscant, he was the "big bad guy".
and congratulations to The Shadowlands for defeating him around the same time.