[jsmr]

For instance the terrain on certain tiles is grass, but I noticed some .ACE files are fields etc and are placed in certain areas.
It is possible to change specific texture tiles in specific areas on a route to say from a grass only texture to a ploughed or agricultural field, or grass where it wasn't, etc?
possible
I wasn't sure if it's possible on an existing route or whether its something that can only be done during route creation.

[jared2982]

It is part of the route building process but it can still be done after the route is finished. Either the entire tile can be changed or a custom tile can be created to work around any items that may be on that tile like track or roads. I’ve been away for a while so I will let someone else explain how to do as I’m sure I’m out of date and TSRE can probably assist with this now.

[jsmr]

Awesome thank you.

[Weter]

Hello.
TSRE5, despite MSTS RE (which allowed to add partial textures too, IIRC, and place small patches, named "transfers"), allow split tile on many square parts, setting texture for each individually, overlay satellite image (with MSTS RE that could be done too, as many routes show us), and even paint on tile texture with brushes of custom shape or along tracks, roads or, say under selected objects.