When I unlocked the "speed" ''acceleration" and "eco" packs, I can't charge them, the charger only has a selection of normal packs, what can you suggest me to do?

And of course, I want to express my gratitude for such a wonderful mod! However, in the future I would reconsider the detailing of some angles of the the train cars

Hiya, sorry for delayed response. I suppose by now you either figured it out or you stopped playing haha. You need to charge those experimental (speed, eco, accel) in an experimental charging station.

I will look into whether I can make this more obvious in item and recipe descriptions

And your gratitude is appreciated :))