I'm not sure if either of these are "themes" -- when I think of themes, I think of what each Vala contributed to the Ainulindale, or a theme for each incarnate race and for Falling. In my mind these are more like suggested music for a scene.
For the first meeting between Finrod and Men, maybe a reprise of the Third Theme (from the not-yet-written Ainulindale): Strange Gift + (something to represent Elves or Noldor). And/or something to represent the excitement of discovery, for both parties.
And I hope it isn't until Season 5, but maybe some epic music for Fingolfin's duel against Morgoth.