If I had to homebrew a quick fix, I’d suggest something along the lines of “When making an attack, check, or saving throw while under the effects of a spell or feature that allows you to add additional dice to the d20 roll, such as Bardic Inspiration, you may only gain the benefit from one feature on a single roll. If multiple features would add dice, you may choose which feature to add the dice from when you roll.”
You don't need to because bounded accuracy doesn't need to exist, often it's actively detrimental. See the common houserule that some checks can't be attempted without proficiency.
A thought I just had, Tymora took followers from Maglubiyet, and then got them to steal a hammer from Moradin, are you sure she isn't doing a general powergrab from other gods?
I don't think that fits with the spirit of the item, and leans back towards the monkey's paw. What you have to do is make it sillier. If they wish for 100gp, they can take out 1sp from their pockets at a time. If they wish for a million gp, it's a random location each time.
The touch of your shadow-wreathed hand can siphon life force from others to heal your wounds. Make a melee spell attack against a creature within your reach. On a hit, the target takes 3d6 necrotic damage, and you regain hit points equal to half the amount of necrotic damage dealt. Until the spell ends, you can make the attack again on each of your turns as an action.
Does Razira speak Celestial?