Hi
I have no idea if that is possible. I am completely overwhelmed with modding myself. You are welcome to try, but unfortunately I cannot really help with that either. I only updated the mod because it was easy. (So only change the Factorio version) Otherwise I would have had to wait until someone who knows more about it does it.
Well I wish you a lot of success then. :D
Edit:
I just looked at the mod and found that there are several locomotives that are much faster than the normal locomotive.
Then it occurred to me, are they really driving at their "normal" speed and thus ignoring the speed limit? Because in my experience, the trains only brake when they pass the sign.
That means, if a train arrives at 1000 km / h and passes the sign, it brakes but is still very fast for a long time.
It would be great if you could look at that again and then let me know if that is the case.