I also don't understand this Harmonic Hero, either. Plumeria could've worked with a lot of people, but Caeda? I'm not against her or anything, but it's a weird and unsatisfying pairing to me. Would've preferred a Trianda/Plumeria or Freyr/Freya.
ALSO, GOD HAS BLESSED ME. I got my favourite goat man on my FREE.SUMMON. I'm SO happy. SO HAPPY!!!