I had a sort-of similar idea for a civ, except it would be led by Brigit, be comprised of some mortals and some unfallen angels of fire who joined other gods, be created through an event option on Brigit being freed, and be focused on redeeming Bhall and the fallen angels of fire.
Anyway...
I guess you could have your race worship those unfallen angels who joined with Lugus and Basium, but I don't know about the scattered spirits of the dead angels.
I don't know what would happen to their souls, since presumably Bhall withdrew her ara from them. Since Kael said (can't remember where) that Brigit can die permanently in the lore, I would assume they're permanently dead.
And I don't think permanently dead angels can come back, but MC or Kael probably know more about that than me.