Very believable interaction between the canon characters!

And it's good to see more of your OC Rhovanglin.

Interesting! The Gates of Summer festival, as described in the Fall of Gondolin, always seemed rather strange to me but here you've made it seem very natural. I like the idea of it being a Sindarin tradition, too.

I'm also glad to see a story with Idril, Aredhel and Lalwen bonding! The tiny bit of astonomy made me happy, too.

Randomly, I thought this bit of description was really nice:

"...had shorn their dark hair so short that it lay like a smooth helmet around their heads..." 

Probably a strange thing to like, but I thought it made a very sharp mental image!