Yes, I've seen the graphs. When I discuss bass extension, I mean the earphone needs to be able to present a discernable note. The ER4S below 60Hz doesn't. You can throw 20dB EQing on the bottom end and get a 30Hz tone from them. On the other hand, I can use a variety of other earphones and get a 30Hz tone more readily, sometimes without work. The CK90Pro is a good example. It's a simple 2 BA driver IEM, but the bass extends all the way down without needing EQing. The notes are just there. They aren't robust like the UM3X, but even light in body, the notes are there, with zero EQing. Stepping back to the ER4S, the notes are not there. Bass is well represented down to around 60Hz, then very little after that. One could say the same about the frequency response for the SE530. There's another earphone with a graph that shows a flat, extended bass line. However upon listening it just isn't there. The SE530 rolls off early and rolls off a lot. It can't produce a 30Hz tone to save its life. It just can't. It can barely produce a 40Hz tone with a ton of EQing. Yet, the graph shows it's flat and extended. I've seen graphs showing the Triple.Fi 10 has the same kind of low end response, but the sound is entirely different, a lot more midbass and better bass extension than either the ER4 or SE530.
Sometimes it's not always about sound but also the ability to articulate and fill out a note. Sometimes it just takes a good driver to do this. The Custom 3 is a good example of a good bass driver. Low frequency notes are well defined, articulate, and dynamic. It rolls off a little on the bottom but responds great to EQing. You may even experience better results with your remolded pair.. Just because you can hear something played doesn't mean it's good. The ER4S is one that is like that. Yes, you can hear notes, but they are not well represented. You'll hear something there being played, but it's not a good representation. I'd prefer to have a good representation.