Realistically, the size of headphone drivers and the proximity to the ears all increase the difficulty of making a excellent harman target headphone. This is why you see things like Susvara or HE-1 demanding some of the highest prices. A 3" speaker driver on the other hand, can easily get 95% to harman targets and a multitude of other potential sound signatures. So consequently, if you have a headphone that is leaning towards Harman but doesn't quite make the grade, then it can be hard to find a good profile from that point. Sometimes you find a EQ that sounds good but then realize another part of the FR became imbalanced. So a headphone that is more V shaped or imbalanced to begin with, can perceptually be more "fun" to EQ but NOT because it's accurate. It's more fun because it's less linear to begin with. There are other sound targets that people can tune to. I would say that many ZMF headphones (excluding some, auteur is more harmany if i remeber right) go for a more linear treble response with 6khz being a distinct peak. Meze Lirics also have a very good spin on a neutral U shape, which creates a good sound profile. So not saying it's wrong, but a harman headphone will technically still be more accurate, yet the results will probably be more underwhelming.

Yeah. I have a calibration mic, which I can use in conjunction with ear simulator measurements. So I can flatten out the response then bring the EQ back to harman from the ear measurements. That makes it harman but even smoother than usual. And the end result, is usually you always percieve less dynamic-range. It's not always the driver being bottomed out, usually the driver performs fine but it just loses out on DR. So that's something to consider with harman.

Plus, many people including myself prefer cutting either the mid highs or treble a little, to make harman less harsh. It's more of a perceptual thing though.