Boutique parts don't automatically create the perfect audio component. There is intrinsic or fundamental design that is most important, parts only as good as the circuit they're placed in. The other possible issue with boutique parts is they are generally uniquely voiced vs generic parts. First off they are more likely to provide greater transparency/resolution vs the generic so voicing will be more apparent. Voicing or presentation also more individualized in the boutique part, particular design elements such as metallurgy specifically chosen for their presentation. I don't find it surprising in regard to @larryi post the maker didn't find those particular Mundorf caps pleasing. I've experienced Mundorfs with the silver, not going to work well in every situation, highs may be spotlit, mids thinned out, bass less full. For this situation a nice copper Jupiter film cap may have been the perfect cap.
Point is you don't just go into speakers or any component and just willy nilly put in just any boutique parts, one has to do their research, plenty of info out there on voicing or presentation of these parts. And even then one may have to experiment with a variety of these parts. I went through three different caps, two resistors, changing out various positioning of different types of hook up wire in my custom build 300B amps to get presentation I wanted. Even more changes with the crossovers in my Klischorns. And since we're talking about speakers, crossover mods are probably without a doubt where one can actually easily hear substantial change for the better. binding posts and internal wire probably should be the least of your concerns. The big changes far more likely to come from caps, resistors, inductors, I'd really emphasize the inductors as responsible for amazing differences in tonality and transparency/resolution.