I think the main problem you’re having is too many defensive heroes. I like to use 2 healers and 3 hitters on raids, and generally go for one healer and 4 hitters on titans. Using BT and Delilah on raids is good, and then Dom, Caed and one other hitter would be ideal. Grimm would be awesome, as would Falcon - as @Fledoble points out.
Delilah on Titans is a bit trickier, because her minions take valuable time to go through their hit animations. you could just go with BT as a healer and see how you do. Grimm, Scarlet, LJ, Melendor and to a lesser extent Falcon and Tibs are all good choices with high tile damage numbers. Falcon and Tibs have lower damage numbers, but make up for it with their own brand of defense reduction.
Boril is great on defense, but he just sits there on titans, for the most part, unless you use mana to power him up immediately, which I don’t recommend.
Assuming you don’t have the mats to ascend your 5*s, I’d think your priorities should be Grimm first to replace Boril, then Tibs and Falcon so you can double up against yellow and green titans, then some mix of Scarlett, LJ, Mel, or even Chao depending on which titans/tanks you see most often.