I actually like the lillies as a concept so hear me out.

Make lillies proc off regens instead, say even as low as 5% per tick (so in a 4-man 4 roles at 5% every 3 sec with Medica II, 5 roles with regen on tank). Lilles act similar to Aetherflow, with abilities locked behind lillies and consuming 1 lilly each. A few could be a 15% shield to one person, a % mp regen and a flat tp regen. Maybe another oGCD heal but honestly we don't need that. Maybe even some dps skills. Then there are 2 abilities that cost 3 lillies, one that reduces a cd by 20% (this is fine and usable with more reliable lilly gain) and another is a 10% shield to the party. This encourages overhealing to the extent they want WHM to do in SB but moreso to get things we can actually use. The mp/tp regens are nice to have in anything, but work really well with AST to push raid dps. As much as I don't want to admit it, AST pumps out better heals than us so we would be the SCH in this scenario, but we still have burst healing so we can take over in add phases while AST pushes raid dps. With these lillies we don't necessarily have raid utility to push dps, but we can be the best support there is, still boasting amazing healing and supporting our support at the same time.

Confessions need to be their own GCD with an oGCD to use them, dunno why they also had to be locked behind rng. Throw a stack up to 3 on someone, pull the trigger and bam like a 700 heal at full, 500 and 300 at 2 and 1 stack. Stacks last 30sec. I would say this is a tool more for the "I shouldn't dps because I am a healer" healers, but can still find a niche in raids. Maybe another 3 lillies ability could be to give the party a confession, pop oGCD after room AoE and Medica II to top everyone off and get lillies back.

With this system we have options, both preemptive and reactive and a little utility to boot, and using consistent lillies to spam Assize would almost on its own solve our mp problem and free up that cross-role slot and the constant healing means no one dies, which means we don't need swiftcast. And if anyone does die the constant regens mean WHM has ample time to hardcast raise. Take Protect, Esuna, Cleric Stance, Eye for an Eye and Largesse and bam you got a badass healer with the best burst damage for those squeaky clean dungeon runs and dps checks.