About the only use for stopping signals is if someone is tailgating you really hard. I don't believe I've ever seen it used.
Otherwise for turning just put your right hand out to turn right and your left hand out to turn left. It's legally accepted almost everywhere and it's understood by almost everyone, unlike the left hand signal to turn right.
That weird signal using your left hand to turn right exists because drivers aren't able to signal with their right hand. It's not necessary on 2 wheels.
Thing is, cleaning up slop, AI or otherwise, is miserable, slow, difficult work. It's why we get caught in rewrite traps.