Hello. Are the er4 sealed? I mean is the any vent? If you try to blow into the sound tube, does the air pass? In Shure se 535 it does. So you can easily put the triple flanges deep into your ears. I made diy er4-b sealed and can not insert them deep enough because of air pressure on the eardrum.
Yes, they're sealed (and so should be the Shure, however yours might have a tiny leak around the MMCX sockets). The key to proper and harmless insertion is doing it slowly. Pulling your ear with one hand while you use the other to insert the earpiece is another. And finally, you could just barely moisten the tips with water to reduce friction.