It could certainly be done....A manufacture could say.... switch the 3mfd capacitor with a 4mfd to lower the contour between the mid and tweeter or 4 mic to 3 mic to raise. or have a simple Lpad with plug in resistors...with instructions... current tweeter has a 3db pad, change R1 to this and R2 to this to increase to a 4db pad.... etc.... some changes can be done for taste. Or plug in these 3 parts to add a notch filter to take the peak out.
Overall, most manufactures try to obtain a flat response....
Overall, most manufactures try to obtain a flat response....