Question from complete newbie to this franchise... Why no custom image uploads?

vector image file size are smaller than bitmap/png and quality(clearness) is higher.
The problem is there should be a tool on pc for edit those vector image and uploaded into forza.

Forza has limited shapes, vector graphics use any shape, any points X/Y. The cheat editor that uses squares can be improved a lot though. I could write an editor that would use any of Forza’s shapes.