to be honest, I'd personally leave them to it to sort out... these things take time.
Is there any way of putting in another set of roosting bars, so that you can put the Spex in the coop but not on the same bars? Then at least they are safe out of the tree.
I'd be inclined to just bundle them (gently!) into the coop and let them choose where to roost.
Encourage them in with a treat of corn or something at "bedtime" (whenever you notice the RIRs are going in)
Our chickens are all penned in various runs and coops (too dangerous to free range here) and we always had trouble getting them to go in at night. In the end, we agreed to just leave them to it - when they are very young I pop them inside when they are sleepy, then we leave them out. By the time winter comes, they choose to go in all by them selves & I just shut down the doors at last check.
Obviously your set-up is different, but how long do you want to be climbing trees?!