I am all for experimenting.
What I would do in your situation: after removing any contaminants from the inner diaphragm surface and backplate surface with a fine brush, press-fit the diaphragm ring onto the backplate assembly, as it originally was constructed, but do not under any circumstance use adhesive, including cyanoacrylate! Just press-fit for now, to see whether the capacitance you dialed in will yield good frequency balance.
If the sound is too boomy, increase the space between backplate and diaphragm ring by using less force on the parts you pressed together, and if there is too little bass, do the opposite.
Once the sound is ok, do not change or touch anything, but apply a couple of drops of E6000 to three or four spots all around the circumference at the gap where backplate and diaphragm ring meet, to permanently arrest the current setting (E6000 can be removed without residue, if you need to readjust later on).
Please report back with your results!