[npteljes]

Your comment made me look this up, and it turns out that the copy-paste and blueprint functionality goes against the core ideas the original OpenTTD devs have. So it principle, not a technicality.

I have found an OpenTTD fork though, CityMania, which has several quality of life patches, including a copy-paste tool. I have just tested it and it works, kind of, but it doesn't copy terrain elevation, so junctions have to be made with bridges, instead of tunnels, to be able to be automatically replicated.

https://citymania.org/downloads