Really useful map!
My only observation is to emphasise that step free access to the platform does not necessarily mean step free access to the train. At Montpelier, for example, the platform is accessible, but there is a yawning chasm between the platform and the train... I don't think I've ever seen anyone getting on or off in a wheelchair here, but I've seen a fair few people struggle with buggies (and even helped a few!)
We could certainly add a "Mind the Gap" warning in general.
Montpelier is shown in green - so fully accessible to category A standards.
I was a little surprised to note that Pilning is only a category B. From my knowledge (having spend quite a long time waiting for the next train) the only platform there has good wheelchair access into and off the train via the train's ramp. Is the selection of yellow (category B) an indication that the absence of a footbridge is only temporary and a like-for-previous-like is planned for installation, which (as like for like) would not provide for wheelchairs on the Wales-bound platform? Or am I just dreaming of what many people think would be an excellent Christmas present?
