A Trickery Cleric who is bad at Stealth and Sleight of Hand and doesn't have proficiency in Deception isn't going to make great use of Disguise Self, Pass Without Trace, etc. AND they gave her high Strength to boot, which tells me they want her dealing damage up close?
Stealth - Blessing of the trickster = Advantage on stealth, pass without a trace = +10 to your roll. Thats a pretty hefty advantage for anyone.
Disguise self - no modifier needed. The only thing that matters there is an insight check from the other party that needs to beat the DC of your spellcasting ability, wisdom, to see through the illusion.
Deception - Charisma, - you can charm, and can cast guidance to add the D4 (as Disguise Self and charm are not concentration spells) to add to whatever change to the DC is involved with the disguise self. Not being proficient in it is a shame, but I dont think it outweighs the advantages you get from the rest of their toolkit.
There ARE negatives to stealth and all that, but realistically she doesn't need it. Shes either being a face or getting past someone with the rest of the party. I am having a hard time thinking about a time where shes going to go forth and be the stealth hero while everyone waits behind.
The biggest gap is the duplicate that is just a distraction in this. Not being able to disguise self, cast a duplicate, and then cast spells through it changes where she needs to be. Having a duplicate that has mirror image on it is one HECK of a distraction for the enemy that completely wastes their time.
But, without the duplicate, still highly functional and i have used disguise self against the gith and other things to good effect. I just never caught myself going "argh! if only her [stat] was higher!"
