While reading your post is astounding.
100% drawing cirdan as a slightly eldritch elve.
But how did this start because ilmondid moved a island to valinor in the beginning and cirdan stayed at the shore.
You could it make a little bit angst.
Like the first cirdan drowned?
And ulmo moved by OG cirdans wish to help the elves and love for the sea and Ulmos own wishes to help and love for the elves mingled together and:
Ulmo/cirdan just pop out of the ocean on the shore like a little eldritch accident.
It would also work well with the "he came to them in a dream" part that finrod and turgon had about ulmo!
And his power waned it the rivers because he is simple kinda a little stuck in a little elven body sry 😔 ~
Not that he minds but ppl where questioning his beard so he just made a little lie that:
"very old elves like me grow beards"
like there are not very old elves in valinor that then should have beards too?