Hey,
Love the mod concept and the file structure, very organised :D

I had a bug report come across on the angels forum/discord/github:
[https://github.com/Arch666Angel/mods/issues/520]

After an investigation it occured that we may have forgot to inform you of the combination of the 3 angelsaddon-train mods:
angelsaddon-petrotrain [https://mods.factorio.com/mod/angelsaddons-petrotrain]
angelsaddon-smeltingtrain [https://mods.factorio.com/mod/angelsaddons-smeltingtrain]
angelsaddon-crawlertrain [https://mods.factorio.com/mod/angelsaddons-crawlertrain]
into a single mod:
angelsaddon-mobility [https://mods.factorio.com/mod/angelsaddons-mobility]

As a result of this, each of the train entities are created (based on settings values, 0 for disabled, through to 5 tiers) in the data stage...
Recipes and techs are updated in data-updates so they are quite accessible

For ease of reference, the mod setting triggers are:
mod exists:
angelsmods.addons.mobility
each train enabled (alternatively, you can check if tier_amount>0):
angelsmods.addons.mobility.smeltingtrain.enabled
angelsmods.addons.mobility.petrotrain.enabled
angelsmods.addons.mobility.crawlertrain.enabled
each train tier:
angelsmods.addons.mobility.smeltingtrain.tier_amount
angelsmods.addons.mobility.petrotrain.tier_amount
angelsmods.addons.mobility.crawlertrain.tier_amount

The train names themselves have not changed in the migration to the new mod, but the access to tiers has been improved a tad.

Cheers in advance.