It isn't about having endless time. There is real industrial research out there about how to match Pantone X in ABS (and nylon, and all sorts of other plastics) to Pantone Y in paint. It should be quite literally an exercise in looking up a chart - the work has already been done for them. I never expected, for example, to see the same colour being listed on that chart for Bumblebee for both plastic and paint - one should be different to compensate for the difference in how they reflect light (and also perhaps to account for the underlying plastic colour).

Now that I think about it a bit more, though, perhaps they're having real issues with the dyes in their plastics, and getting them to come out the right way. Would explain a few things...