Will chopped up dried fruit still be fine to use after it's been sitting in the fridge for about 3 weeks?
The process that preserves fruit in a drying situation is the significant reduction of water activity in the product, which inhibits bacterial growth.  It is impossible to know how much you re-hydrated the product, but you certainly increased the water activity significantly.  Then, you added other ingredients.  All of this increases the potential for bacterial growth.

Of course, refrigeration also slows bacterial growth, however, for me, there are too many unknowns here, from the source and condition of the fruit, to the nature of the additional ingredients and the time between re-hydration and refrigeration.  Three days is probably fine.  Three weeks would concern me, and I would not recommend use.