(kfs - this guy doesn't have frets)
I find it fascinating that we have people here complaining about these TI low tension, nickel, flat wounds, being too bright or thin sounding. Turn down the treble to compensate for using nickel flats??? But I acknowledge that several well-respected members, including dela and dfung, have made the thin-sounding charge, so it's quite curious.
I leave the treble flat and actually turn down the bass a lot, though I then add a moderate boost using the SF-2, with a low pass set at 80 Hz with Q/damping a little beyond 1:00. Don't get the plinky G problem, but maybe more on that later.
And yes, plucking with a fleshier part of your finger, or angling your fingers back toward the bridge so you use more of the side than the tip, will round out the tone a lot. Or you can be punchy and brighter when you like, they seem very flexible to me (in more ways than one).
As for nut height, the general rule for fretless is that the strings should very nearly come down to the end of the fingerboard. 2mm on the E would be excessive for a fretless, I think. On my B string, I can't quite slip in a playing card without friction, about a 1/4 away from the nut. That would be roughly 0.01, or 0.254 mm if my math is right (wasn't a moment ago...).
Remember the general rules here. If you have buzz problems in the first 3-5 frets, then maybe it's a nut height problem. If the problem is higher up the neck, then first check the relief, and second check the bridge height (these interact somewhat). Nut height is really a fine tune for the first few positions, after you have the rest right. But as a starting point for fretless, the nut should be low enough so that the strings are very nearly grazing the end of the fingerboard.