Issues after changing from overloaded trains by ptx0 to change to this version. My trains magically connect to other trains. Wagons disconnect by themselves blocking track. Train groups keep deleting themselves every time a train leaves a station, even after deleting my groups and re-adding new ones completely. Don't want to start a new game so reverted back and issues stopped

This version works by deleting and respawning wagons to make the trains actually heavier instead of a script slowing down the acceleration. (And not braking)
I guess there are some side effects.
Can You explain a bit more detailed what you observed?
When do Wagons disconnect? Maybe on a curved rail?

Okay, should I need to fully remove all my trains and rebuild them then?

So I noticed a pathing error notification on game load so once clicking the flashing icon it took me to some wagons left stranded on a straight part of rail track. Nothing was inside the wagons (not sure if the wagons were supposed to be loaded or not at the time). I hadn't noticed anything at the time by visually seeing it, but as my game went on I was noticing stations weren't being serviced and some of my trains were missing wagons. So I normally have a 1-4 train setup ( loco<wagon<wagon<wagon<wagon ) and when inspecting the issue a couple of my trains became merged - ( LOCO<wagon<wagon<wagon<wagon<LOCO<wagon<wagon ) with 2 wagon missing assuming these were the ones left stranded on my rails. So I had deleted the train and rebuilt 2 of them back, after a little while, once again my trains merged again but I hadn't physically seen it

The other issue is my train groups were deleting themselves. Once I build a train. eg. Stone, I would make a group to add new stone trains to the shared orders, however every time a train would leave a station my train would remove itself from the 'Stone' group and become unassigned but adding the train back to the group would remove itself after it left a station once more. if all my trains removed the group assignment I would then lose my group overall

Just reloaded my save with this mod to check it out again. It happens at my stations. Because my signals are right at the tail end of my trains, and the next train is waiting to enter the signal, the front is literally a tile away from the back of the other. So when a trains gets ready to leave it quickly flashes (probably the respawning you mentioned) and doing that it connects the train behind to the rear of the last wagon. Not sure why my wagons disconnect though as this happened at a different location. This time it was at a station instead of a random section of track

Breaks train groups and interrupts. As in trains get removed from groups and have all interrupts cleared as soon as they start moving.