Have you try sv thunder carol and killing yag First? Carol can block woc stuns completely so it should work in MT too.
Old areas and new areas are actually completely different beasts when it comes to resisting. High content level mobs in old areas tend to have obscene levels of magic accuracy to compensate for being level 99 and no +stat/magic evasion vorseals apply.
Ever since Vex/Attunement were fixed resisting stun from Sovereign Behemoth (135) or burn from Sarama (135) or anything from Tumult Curator (145) is substantially harder than resisting Warder of Courage. (~150) except for Bard debuff songs.
I think Unafraid of the Dark falls under old zone rules. I think the best bet is to get positioning down, heavily buff attack (with outside buffers if needed) and drop the yagudo quickly.
That said it's still possible to Lightning Carol the WHM without doing everyone else as someone already said. Also making sure you nocturne or addle too. Entrust attunement is a massive sacrifice I feel. You'll probably want to entrust fury but it depends on your other buffs/debuffs.
Magic evasion is better than resist-stun. I'd only use resist-stun if you know you won't resist or partial resist the stun.
Shrieker's cuffs are a low magic evasion piece. I would use Pinga Mittens+1 or Volte Bracers unless silence is actually a problem.