Given that the 94dB is loud enough to permanently damage your ears with extended listening, and 114dB is loud enough to permanently damage your hearing in minutes, I'd say it's totally acceptable.
The relevance of those distortion graphs is mainly in bass EQ. I've recorded 0dBFS sine sweeps of my headphones on my miniDSP EARS after setting amp levels towards the upper end of my normal playback levels and it's around 84dB at 1kHz, but then with nearly +10dB bass boost EQ that would pull the relevance of Amir's distortion graphs up to around 94dB in the bass - so for me I just make sure that the 94dB distortion line would be clean in the bass and hopefully no glaring problems higher up in the frequency range at that same 94dB - but you won't really be listening to music at 94dB except in the bass so you can probably assume your actual experienced distortion level is lower than the 94dB line everywhere on the frequency response except in the bass. That would be valid for me at my listening levels. I suppose if you listen ultra loud at times then you'd want to push that up to the 104dB line in the bass and start giving the 94dB measured level a bit more relevance in the areas above the bass. But you won't be damaging your ears by listening to comparitively high levels in the bass - that's why H&S Guidance is based around measuring noise that has been A-weighted - ie reducing the contribution of the bass to the measured dB level. So it's not as simple as just saying that 94dB or 104dB is enough to make you damage you ears, because it depends on where in the frequency range you're referencing that measured dB level.....and besides the 94 & 104dB levels you're quoting are Amir's distortion graphs which is referenced to those values at 400Hz, and the rest of the frequency range of that headphone that he's measured sits relative to that.....so you'd have to work it back from that where your EQ boosts would place you for various parts of the frequency range for that headphone.....it's a bit hard to explain, but it's not as simple as saying "94 & 104dB will make you go deaf". I think it would be useful if Amir additionally included an 84dB measured level of distortion in his headphone reviews - that would be more relevant for me (& probably others) for distortion levels I'd see in areas
above the bass....due to the mechanisms I've tried to explain in this post.
So for me, if I reference the IEM in this review, then I think I'd be ok with the distortion levels as it's just the blue line that is relevant (for me):
And given that in the frequency response for the headphone that the 20Hz point in the bass is actually above the 1kHz point, then you don't need to boost the bass (so you don't have to worry too much about the higher distortion seen in the bass in this IEM as it's not gonna be boosted):
The 2kHz peak in distortion also doesn't need to be EQ'd up in that area either, and given that we know we don't really listen to 2kHz at 94dB anyway, then this will be lower than the 1% distortion at that point. That is the worst part of the distortion graph, but given what I've been saying in this post, I don't think distortion would be a problem for me with this IEM. (would be cool to see an 84dB distortion line measured).
(Yes, the target has been placed too high on the frequency response which makes it seem that the frequency response EQ points I'm bringing up don't make sense, but it's more easy to understand my points if you lower the target by around 3 or 4 dB so that it's aligned at 1kHz)