HG didn't sue over the Atlas, Shadowhawk, and Locust, they sued over a large number of the mechs that are 'unseen', which they did hold the licensing too
This would be the original Marauder, Rifleman, Archer, Longbow, and Warhammer, which are all Destroids from Battletech.
Not to mention the Wasp, Stinger, Phoenix Hawk & Crusader, which are Iconic Macross Valkyries.
HG did not sue over the Dougram mechs, those had a separate rights holder that settled w/ them outside of court, those mechs are Shadow Hawk, Scorpion, Wolverine, Thunderbolt, Goliath, & Battlemaster
The Locust was from Crusher Joe, another rightsholder entirely, who also settled outside of court.
To my knowledge, the Atlas is a Battletech original design, and nobody sued over it.
Harmony Gold has fucked with a lot of shit, but like it or not they definitely have the Macross License in the United States and Battletech using their license w/o permission was a for sure nono.
Fun ADDITIONAL fact, Gen-1 Jetfire, of Transformers fame, actually utilizes the design of a VF-1 Armored Valkyrie from Macross as well (infact the toys were literally made from the same mold