In that point, the given manufacturer can rightly take exception to such changes.
Eg, the odd speaker manufacturer, to avoid this problem, makes potted (sealed in epoxy) crossovers and single wire termination only on their speakers.
Just so the customer, who may be suffering from extremes of audio nervosa and tweak mania, can’t make changes that take the sonic result of the speaker..out of the area which the designer and builder of the speaker intended.
why is this issue of misrepresentation a problem?
Well, we are all different in our hearing and thus systems and build. All things sonic, felt, seen, and so on, are individual in their input and internal interpretation. Naming can be fairly consistent but that is the only part that is even remotely consistent and in consensus: The language of descriptors. that’s it.
To the point that the same cable, the exact same cable we may be selling, is considered by different people, in different systems to be harsh, slow, fast, etched, screechy, beguiling, incredible, spacious, 3D, bass heavy, bass light, lacking in detail, extremes in micro detail, all polar extremes that you can imagine, as descriptors from people. All of the same cable. From excellent to crap, to best to bad, all the same cable. Literally the same cable.
One’s given messing with an umbilical (or any other cable or component, for that matter) can be detrimental to the representation of the gear to other people in other systems.
There is some meandering toward a consensus in expected results, but it is marginal, at best, in the long view.
Since we all have individual aspects of internalizing sound signatures, it (consensus) will generally be marginal at best. Otherwise this business and forum would not exist. The solution and the problem are wholly intertwined and inextricable from one another. Pretty well for as long as humans are going to exist.