Yes, I've also seen the measurement from your link. I've also made a custom 24 ohm impedance adapter for the ER3SE (over 1 ohm because it's hard to get the right amount of resistor) because I saw those thread.
However, after I directly compared it with the ER4SR, the sound is not close enough. The ER4SR is still brighter. I again added the impedance value to 75 ohms. Pretty close to ER4SR but still a little less bright. And ER4SR is still a little more detailed which I believe this detail retrieval capability will not be able to get with the ER3SE + impedance adapter because use of different driver.
Some of the things that make the ER3SE + impedance adapter not the same as the ER4SR are:
1. The drivers are different
2. The placement of the resistor is no longer in the cable like the old ER4, but the resistor is inside of housing, so changing the frequency response is not as easy as the old ER4 which only equalizes the impedance value.
3. The graphic on the link you sent is ER3XR vs ER4XR which may differ from ER3SE vs ER4SR.
I recommend an ER3SE + impedance adapter of 50 ohms and above. 75 ohms worked well for me, although it's a little less bright than the ER4SR, but the sound is still very accurate to my ears.