As far as Shadowheart goes, she's roleplay before optimization, which I think its okay, but seems out of place since we can't get to 5th level whilst most of the the later threats are quite daunting. Invoke Duplicity is also quite lackluster because any enemy you want to use it on will either die in a few hits or leap/teleport around the battle. Pass Without Trace is good on paper, but isn't necessary given the turn based movement you can turn on.
As for Clerics in general, I think they're okay. Sure, weapon attacks are majestic with high ground, but Guiding Bolt is extremely effective in the same regard (though 4d6 has a ton of variance in damage output). Inflict Wounds is the same thing, but you instead have the backstab bonus - highly variable damage, but still a lot for a first level spell.
Admittedly, Trickery Domain is wasted in a straight up fight, Life Domain can be skipped if you manage food and rests, and Light Domain is the biggest winner in this format. Radiance of the Dawn is a solid Area of Effect that you get back on short rest, Burning Hands is a nice alternative to Guiding Bolt/Inflict Wounds, and Scorching is nothing to sneeze at either.
While many 5E tabletop players know Spirit Guardians is one of the best spells in the game, I don't believe it will do so well in game. If Burning Hands is any indication, a 15ft radius will not cover a lot of enemies, especially with Larians emphasis on verticality. Doubly so, the amount of concentration checks will mean Spirit Guardians will be knocked aside quite easily, though that might change if Reslient and War Caster feats are added.
In which Light Domain will do quite well for good old Fireball if we get 5th level anytime soon, or 6th level if we get two uses of Channel Divinity. If Druids are added (given the somewhat incomplete Druid animations and abilities), then Magic Initiate for Goodberry might make Life Clerics relevant (though ironically that goes back to food and rests).
Overall though, I'm quite enjoying a Light Domain main character even with Shadowheart. Base Cleric spells of Prayer of Healing, Healing Word, Guiding Bolt and Inflict Wounds are quite relevant, though I'll admit Agonizing Blast Warlocks and Speak with Animals Rangers are more meaningful to party composition and all.
