yeah.. erm.. I kind can't see how conductive paint CAN be transparent cause the various materials used for the conductive coating. The conductive stuff I use is mostly for repairing bad buttons (like TV remotes where they don't use a proper button but a bit of rubber with a conductive paint coating to work as the contact point.. very cheap poor method but it works for it's job, though when you put alot of pressure down along with minor rubbing which happens due to that fact that rubber isn't solid and people start to push down harder when they start to rub, which rubs even more) but... to be truly transparent? not much call for it.
for the train side, I would say it's mostly wired. far more trustworthy then painted.