Will BM3 show CEL for post cat o2 sensors if cat checking is turned off

[ArabM6]

Hello, after 3 years of selling my bmw M5 e60 i caved in and bought another M car, so my new BMW M6 F06 2014 (new to me) has BM3 already installed on it due to it having a catless downpipe installed and no post cat o2 sensor codes... so the cat checking must be turned to off which is what I concluded... my question is if the secondary Post cat o2 sensors will throw a CEL if one of them is fried, I know that they are also responsible for monitoring fuel trim as well and not just for checking cat efficiency. Would really like to know if its possible to get a code for those o2 sensors if cat checking is turned off in BM3 if one goes bad.

Also if it wont ever throw a CEL even if one of the post cat o2 sensors goes bad, does BM3 prevent it from showing shadow codes for those sensors or will they still pop up on a code reader. Much appreciated.