Pretty much all very true, but being a Chemist/Chemical process engineer by qualification and inclination, I will stick with my statement that it is totally impossible, or at least to any extent that could be detected compared to a spec' and/or without before and after measurements.
For instance, to re-etch a foil and hopefully increase surface area and hence increase cap', the dielectric would have to be removed, the etching take place and then the dielectric reformed. With no dielectric, it would be a resistor, not a capacitor. I'd bet a lot against that happening, especially in a non-polar as it would be far more complicated than that..
Non-polar electrolytic caps are normally two polar caps with their anodes soldered together, so become extremely poor in terms of volumetric efficiency as you obviously halve the cap' when doing so, though hardly a hassle in something like a cross-over. (An anode absolutely must not become a cathode, but a cathode can perform the duty of an anode).