Joel,
Any inaccuracy is coming from software and hardware outside of and before Cubase even knows about it, so it is impossible for the DAW to calculate anything when there is nothing to calculate against!
As Como has said already, various companies including Steinberg have at one point or other attempted to address the problem with solutions called “Linear Time Base” or Sample Accurate MIDI from Motu. Even Roland have a solution that aims to help with reproduction of polyphonic data over a serial line.
Any idea that a plug in can compensate for something it knows (and can know) nothing about and feed this information to the mix path is sorely misplaced.