I wrote a little macro using KeyMaestro on MacOS to make Bambu Studio automatically assign extruders/colours based on the STL name - it is fairly reliable as long as there aren’t too many plates,
Details are here in the form of a feature request. [Feature Request]. Colouring of STLs based on name
I also have a complimentary fusion 360 macro that automatically names exported STL files based on assigned appearance colours if anyone is interested,