I guess what I'm getting at is can the OG Zero's be considered a reference model without any EQ? I know this is kind of getting into the debate of fidelity vs. listenability...
Edited so it doesn't read as grouchy.
At this point you've seen the measurements. It's up to you to decide if they are close enough to a reference curve that you want to try out. (Also, "reference" for what? Are you doing professional work or are you in a roundabout way trying to ask what is the "best?") No IEM or headphone will be perfect and you have to decide whether the measurements show differences you can live with. Part of this is also due to the fact that the respective measurement equipment is not up to the level of that used for speakers so things are always a little hazy. The physical body itself is the biggest problem. IEMs and headphones are very person-specific because of your unique ear/canal shape so please don't expect universal results or ask anyone if something will be perfect for you. You simply have to do your research and try out what you think is best for the money you want to spend after it is said and done. If there is a good return policy, all the better.
That said, the two 7Hz Salnotes Zeros belie their price and seem to get you quite close to two of the most popular targets, what I'd call Harman 2019 and something closer to Harman 2016, the latter of which has been extremely popular lately. Some people think that the Salnotes work better for smaller ears, with the more expensive Truthear Zeros being better for bigger ears. (I have smaller ears and the Truthears are not an option for me.) But again, you've seen the graphs. Only you can decide if that is reference. Personally, I miss that super low end and have to adjust the Zeroes. In the end, the simplest way to think about this is that there are no IEMs that exist that are "reference" without EQ. Some, however, can be good enough. And, most importantly, as a whole IEMs are so much better than they used to be.