yes I've had both a colonoscopy and a sigmoidoscopy (less invasive colonoscopy).

I'm not sure what the botches are here. In the sigmoidoscopy they took out a couple of polyps, in the colonoscopy (more recently than the sigmoidoscopy) they just did a cancer check-up given family history.

I wish those articles discusses the "botches", I'd like to know since from my understanding these are pretty safe procedures

Maybe just don’t worry yourself with anecdata.