Total remake of the map.
Skipped A4 since the way it was going didn't feel right, so I burned it down and started over.
Changes
End area and bridge got a remake.
Carts start in the ore depository freshly filled with gems.
Open ramp in the back of the depository to drop down onto the bridge.
Added a giant auger that'll kill you if you get too close.
Made a single crossover point for the carts.
The spawns are now on opposite sides of the map facing each other.
Three bridges lead to the main spire from the spawns.