I have the ER2XR as well as the ER4XR and ER4SR, in general on the Etymotics, the bass on them does sound a bit more than they graph, I think due to the very deep insertion and the high isolation. So don't presume you don't want higher graphed bass based off the ER2XR and the graph.
If you genuinely did want less though, the OG Blessing 2 has less, although it's also warmer. I think the Dusk is better, but the OG B2 is also very good, and you can sometimes get this discounted which the Dusk almost never is. It's slightly brighter through the upper mids though.
If you can get over your phobia about AliExpress you'd have a lot more options, I don't know why you trust Linsoul but not well-established shops on AliExpress. Linsoul for that matter are on AliExpress themselves (DD Audio). I have spent thousands on AliExpress without issue. Other reputable Chinese stores who operate both on and off AliExpress include ShenzenAudio (who have exclusives such as the Dusk) and HifiGo.
I am somewhat sceptical that treble at 11kHz+ is going to be a big problem for you at 50+ with self-described high frequency loss. Also, the rigs just aren't reliable near or over the ~8kHz insertion resonance so you can't really reliably tell from a graph whether something is going to have a problematic peak up there. You can tell very broadly whether something has a ton of high treble or if it's very rolled off. But I wouldn't make decisions based on specific peaks over 8kHz, they can be very different in different measurements.
That spike at 11kHz on the graph of the ER2XR is an insertion resonance from the specific insertion on the measuring rig. It's conventionally located at 8kHz at the other stuff, although for most people it will be lower. Where (or even whether) it appears for you depends on insertion depth, you can check this with a
tone generator. Generally, having it at 11kHz is much less audible and much less objectionable than having it at 8kHz, and most people won't even get deep enough to get it at 8kHz, for most, it's 6-7kHz. I get it at 7.5kHz on most regular IEMs. This graph is the ER4 with shallow (yellow) insertion and deep (green). I definitely don't get a sharp insertion resonance like you see on that graph, it's much more like this and the ER2XR actually sounds quite dark in the treble to me. It's very smooth though, with no large peaks. You can see though if you do a shallow insertion you will get a big treble peak, Etymotic is extremely sensitive to this.
Generally, problem sibilance is much lower down than that, it's usually really more the upper mids and lower treble. If you KNOW you have issues around 11kHz, fine, but just if you have this idea it's up there but it might not be. If you don't find the Truthear Zero bright, you are probably safe to get stuff with quite a bit in the upper mids region.
Precog target is basically the 64 Audio U12T, that is where is comes from. U12T is his favourite IEM, so that's the target. Just so you know, that's basically what you are comparing to with that target, one specific IEM. I'm not sure it is the most useful for comparison, even though the U12T is certainly well tuned, no IEM is entirely perfect taking a target directly from an IEM like that you capture idiosyncrasies of the IEM. I'm not sure the dip between 2kHz and 5kHz is ideal, specifically. It's in that target because it's in the U12T.
Fiio are often quite poorly tuned, they are a bit of a minefield. I don't think I'd personally pick either the FH7 or the FH7S at full price but do note, these are entirely different IEMs that are tuned radically differently, a recommendation for one is not for the other. To me, both of those look questionable, but in very different ways. If I had to pick one, the FH7 looks better than the FH7S. I have the FH5, what do you mean by the treble being an "outlier"? Too little, the way it's rolled off? It would be better if it wasn't so rolled off but I am not sure this is necessarily a dealbreaker either, particularly not if you are sensitive to too much up there.
ThieAudio Prestige looks like a possibility to me but it has an insane amount of high treble, if you are as sensitive about this as you think you are, it's a definite no. This isn't just going off the graph, reviewers have commented on this. For me I don't think it would be a dealbreaker, I do have high frequency hearing loss and I'm just not particularly sensitive to excess over 10kHz or so. It has similar high treble levels to the KZ PR1 Pro and the Moondrop Stellaris, both of which I have/had and both of which were very bright, but which I found tolerable. I think this may come down though to whether you actually are as sensitive to stuff up there as you think you are, check it with a tone generator. It's also $1,299, if you are open to spending that much, I think I'd get the ThieAudio Monarch Mk2 which is a safer bet (the $149 in your screenshot is only for the cable).
