First of, my guess is you have not seen the picture of the cable I made on last page - you definitely can buy aftermarket cable with the correct Ety specific MMCX connector as well as the standalone connector itself to create your own cable, if you can solder.
Secondly, there is a very good reason to go for a non-spinning MMCX connector because this thing is known to fail after prolonged use when it is free spinning. A locking mechanism is actually the best way to prevent an untimely dead. The case of your right driver failing is one of the telltale sign there is a misalignment on the center pin in the MMCX socket (which sometime still work intermediately, thus making Ety to conclude it was your cable at fault), one of the most common problem with MMCX. Obviouly the locking mechanism is supposed to prevent a problem like this, it is however not a complete fool proof method. This is an inherent weakness of every MMCX connector out there.