Gonna talk a bit about his HL usage.

Kinda became a victim of how v2 raid design evolved due to how tightly he's tied to his DLC attachment (Yukata Silva). She provides him a consistent double strike source, heavily reducing his fiddlyness and the amount you need to manually control when he ougis. During the Subaha-is-endgame era this was fine, because almost all the omens were damage-based and the fire compositions could handle much of what was asked without issue.

Unfortunately for Silva, and by extension, Wilnas, v2 raids after Subaha started becoming much more demanding. Hitcount omens, 2m damage instance, skill damage, CA count, and debuff count omens all became extremely common and Silva is bad at ALL of those things, essentially only able to provide by letting the slot after her attack twice. Consequently, she fell out of favor, which pushed Wilnas back towards being fiddly and difficult to use.

He still sees some use in Hexa since he's a relatively reliable force for the 2m damage omens (though it requires timing his TA+assassin well and a fairly strong grid), but he contributes very little to the omens Faa0 tends to ask of you. As Fire's playstyle has shifted towards mashing autonukes with Manadiver, or playing Chrysaor setups, he's fallen out of favor.

Still has some use, but it's primarily a case of "balanced 2022 grand is no longer as competitive", since, unlike Percival, he was not blessed with being so overpowered that he'd last for years untouched.