I have s12's with a 2 pin utws5. They can't rest on my ear without pulling the earbuds just barely enough out of my ear to break the seal. I would recommend the mmcx utws5's with a mmcx to 2 pin adapter. This will allow the earbuds to pivot so you can rest the utws5 on your ears like they're designed for.

I have other 2 pin iems that work fine with the 2 pin utws5. Just the s12's give me this issue.

There are merits to this design. You can access the normal enter and backspace with the same hand you're using on the numpad.