David,
I spent some time in 2006 / 2007, and again in about 2011 investigating the internals of Trainz maps. Because of design choices that were made when the first version of Trainz was first developed, it is technically impossible to rotate routes. Maybe if the basic structure of baseboards were completely changed, it might be possible, but this would take a complete revision of the basic structure of baseboard maps, and it would most probably break backwards compatibility.
ns