Yeah this has caught my attention too. There's a fair bit of old Victorian railway infrastructure near me in the northeast and I've been mapping out reported encounters against old OS maps for about two years now. The correlation is pretty hard to ignore honestly.
My theory is its tied to ley lines more than the railways themselves - a lot of those old lines were surveyed and built along routes that follow natural geographic features, same features that tend to mark out energy corridors. So the railway is maybe just a marker pointing at something older underneath.
Would be really useful if people could share rough locations alongside their sightings rather than just descriptions. Even county level would help build a proper picture. Anyone else been doing any mapping on this?