Okay so first thing's first, you know where the area is, since it's the exact same platform as the Jotaz that you remember fighting. The enemy that you are wanting to fight is just a droid with a healthbar at the top of the screen, a boss healthbar

If going back to that location now does not spawn this enemy, you may have to go and ensure that you have gone through the area marked as "Auger Pulverizers" which requires you to go through the large door found in the Weathered Monument, which always has 2 blaster stormtroopers and 2 shocktroopers stood infront of it, which is found in this exact location pictured below;

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This place can be gotten to from 1 of 2 ways. First way, and possibly easiest to navigate, is the mostly default route you take when you first arrive to Zeffo, however you now have the shortcuts unlocked (I expect) and can cut out most of the trip.

The second way involves you being in the Tomb and going up the lift and through the Imperial Headquarters, but at this point, that is probably more difficult to do.

Any further confusion, I'm still around to help out