Hey that's one great call out that could have changed everything. You're right that the Green dragon has Con saves instead of Dex like the rest of them. I missed that completely. In the second combat the Rogue took one breath weapon and passed it's Dex save for no damage when it should have done a Con save for half. I don't remember now what that roll was or if it would have passed the Con save or not, but it potentially could have KO'd the Rogue. The Rogue still had +3 to Con saves + Bless + Ring of Protection + Lucky so there's a reasonable chance it would have passed anyway. The Rogue also has 1 level of Divine Soul Sorcerer so could have also added 2d4 to that save if needed. I never had to use Favored by the Gods. The Rogue would have survived half damage, but would have rolled a Con check to keep Bless up.
In the first combat, during the Rogue's turn I had it roll Perception to assess it's surroundings as it wasn't close enough to attack anybody at that time. I could have had it do it's Wing Attack against nobody just to fly up, and maybe I should have, but I felt like it was a "get away from me" ATTACK option that didn't make sense with the closest enemies 40ft away. The Barb was 2nd in the turn order and immediately grappled it. I think that was just lucky. Had ANY other character gone next and attacked the dragon, I would have had it fly up for sure.
Yes I swapped dragons last minute rolling a D6 to see what dragon color we fought. Honestly I thought a Red would be too hard so gave the options to face the slightly weaker ones instead.
I'll redo it using a Red next time, and I'll start with much more distance. That will give the party a couple rounds to get going and see if I can come up with a better strategy for the Bard. I can also give the Barb a longbow. The Pyro Sorcerer has Eldritch Blast from Spell Sniper so it can hit from 240ft and also not HAVE to spend all Sorcery points on Transmute Spell. I could even "cheat" and swap out one of her metamagic's for Distant Spell which she doesn't have lol.