An interesting idea! We hear of the Ents acting as Beren's allies at the battle of Sarn Athrad. This gives a nice glimpse of ongoing friendly relations--and if I understand your summary correctly, you may even be saying that it was this incident that motivated the Ents to do help Beren?
It is good to see a story about young Dior and also about the Ents in Beleriand.
Well told!