Great project! I redesigned some parts. See here: https://www.printables.com/de/model/585348-accessories-and-improved-parts-for-the-openrc-trac
I also implemented my DIY sound controller with original TEA 20 sounds and virtual inertia:
https://thediyguy999.github.io/TheDIYGuy999_ESP32_Web_Flasher/products.html

Maybe you are willing to share the parts in STEP format as well in order to allow better print quality, especially for curved parts?