Let's get one thing straight. This is NOT my route and I had thought the East Kentucky Route probably well known, but maybe I'm wrong. Point is, after careful testing and ignoring the rest of the session I was trying to create, I now know when nothing else is interfering, left will set to left. Right I can only assume is ok given that's the (needed) original setting. However, absolutely no-way will it go to centre, that's even using a different trigger. As for layout, there is a short straight section between it and a curve, but that doesn't prove a perfect match.
However, to add insult to injury (ignoring the unpainted areas), I have again come across some more weirdness but this time it has stopped the session completely (because I'm behind an AI that can't move). Reason; a signal is red saying "Signal ahead is in unknown state." !!???!! The next signal actually says "Medium approach" and is yellow. Frankly after a week of trying to create this session, if I can't solve this problem, I'll ditch the route. Life is too short now to waste much more time. Although I've seen that message before, it has never happened in over 20 previous tests through that area. I am suspecting (like other routes), it's importing into TANE from an earlier Trainz version has not gone well?