Trickery domain doesent really fit with a servant of Shar but hardly any of the phb cleric subclasses do.
Mechanicly it sort of works. The entire gauntlet were basicly stealth checks or stealth related. Add some assasination ontop of that and thats basicly all it revolved around.
Trickery does have things that aid with beeing stealthy. But thats about as far as it goes.
Out of all of the cleric domains Twilight would fit the best with Shar. Alot of darkness involved in the feats. But yeah thats not an option in bg3.
I think adding some rogue classes to make her an assasin could work. Otherwise a DEX fighter could also thematicly work and would allow her to make more then 1 attack.
Gloomstalker ranger also fits well with the theme. Massive bonuses for beeing in darkness and beeing stealthy (which they do well) and bg3 has drasticly overhauled the ranger class which might make it very good.
Shadow monk powers suit the darkness and stealth theme of Shar. Even if the 'monk' part itself might not.
The way dark justiciars are explained a paladin could work to an extend also work. But 5e has no evil paladin variants outside of maybe conquest. But thats not in the game but Oathbreaker could also fit. Which is in the game.
At the end of the day you have to consider for yourself if you want to play purely on mechanics or if the lore is important as well. If you just want mechanics cleric is about one of the worst classes for her and even with the lore factored in the trickery domain doesent make alot of sense xD
