Tried to use the upgrade planner to replace rails on Fulgura. Both empty (upgrade everything) and specific (I pre-pick that every rail configuration, straight, curved, etc., gets replaced). The result is that it replaces some parts but skips others randomly; it shows the upgrade icon on the rail, the bots come and remove the upgrade icon, but it doesn't replace the rail to an electric variant. Not sure if it's only an issue when a light signal or rail support is at that place. Using the upgrade planner again on missed sections doesn't work. It just shows it will be upgraded, but bots again come and pretend they did it (the icon is gone afterwards, but the rail remains non-electric). End result is a checkered rail line with some parts being electric and some old.

My rail network is a spaghetti mess that I cannot manually replace (in decent time and effort), so the mod is not useful for an existing playthrough. Maybe I can use it as just an electric line to connect big islands, but at that point I might as well cheat with some early foundation mod.