I know that no one answered you back then and that its been a long time, but this is still a genuinely good question.
No one even answered your post, or the other one in the console bug report, and this is not in the bug fixes for 3.1 or the PTR either. The other post from Sancroth got more traction, but it’s about another interaction that got fixed in 3.1, with 哥吉拉 and SnowCrow noting the issue with Loyalty’s Mantle.
It seems like blizzard completely forgot that variants exists. Variants changing the skill tag and the base skill type is kind of the point: the visuals are even for the new Spirit/skill type, so the skill loses the spirit skill tag, and gets the new one!
Pyromancy specific items work when a Sorcerer’s skill gets changed to Fire/Pyromancy through a variant, and it’s the same thing for any other class (Blood variants with the Necromancer works with Blood-only items and Talisman sets, etc.) so why wouldn’t Loyalty’s Mantle do the same? It’s the exact same thing.
It’s clearly an overlook, and no one at Blizzard aknowledged it as no streamer touched these variants it seems. With no streamer talking about it, Blizzard simply ignores it.
Basically, I tried with Centipede skills and variants : None of the variants are affected either by the Vigor reduction cost or the cooldown reduction from Loyalty’s Mantle, making the item useless if you use a variant as your main skill or skill you want a variant cooldown to be significantly reduced. I wonder if you could use the base Spirit Halls of the “original skill tag” instead, but it kinds of defeat the purpose unless all your other skills are from the original Spirit Hall to benefit from CD reduction.
I was hoping to build around a couple of variants, not using Rod of Kepeleke (as this variant doesn’t benefit from crit as its a DoT skill, making Rod damage bonus useless), but the high vigor cost (60) makes it really hard to use when Loyalty’s Mantle vigor cost reduction doesn’t work.
I hope it’s an undocumented bug fix, but I doubt that’s the case.
Edit : Not fixed as of 3.1. And the Gorilla tag still doesn’t appear if you use the main Gorilla Spirit Hall and change to a variant that was a Gorilla skill before. At least the Spirit Hall bonus works, so the Gorilla tag might be a tooltip issue only and cause no issue in game , but OP Loyalty’s Mantle bug is still sadly there.