I think the issue with the different trucks is that it appears the use of the proper Freightliner truck in the BB movie may have been a late decision after his cgi bot mode was designed. In bot mode his windscreen shape, sun visors and curved smoke stacks all match up with details from a Marmon truck, which was probably the truck they were going to use in the movie also, hence the reason the studio series is a Marmon, but at some point they went with using the Freightliner truck in the film. I think this is why we're seeing very few attempts to make the truck mode a Freightliner from the 3P companies and even Hasbro. The engineering required to have the windscreen change shape, the sun visors disappear in truck mode, and the smoke stacks curve/straighten, would have to be on MP44 levels. I wonder if in the eventual BB movie sequel we'll see Optimus get a design tweek so his bot mode kibble matches the Freightliner instead? Then we'll probably see more attempts at accurate truck modes.