Timing-wise, for audio, Cubase should be sample accurate at whatever sample rate it’s running at and would null-test, no?
For MIDI, internally, it’s something outrageously high like 1920 PPQN, since like the late 90’s at least, I think. Automation, as well.
I think the only “timing” thing (not really a timing thing), and that plagues all modern DAWs, is the whole VSTs rendering slightly different each time, which is why a lot of producers bounce to audio (and why Cubase’s missing “Bounce In Place” feature continues to be high on the wish list). This is an issue inherent with most plugins, themselves.
Describe more of your timing problems, I bet it’s a non-cubase issue (DPC latency checker issue, perhaps). I bet it’s VST multi-rendering (or freezing) phase issues.
Try printing those tracks to audio and I bet the issue goes away. Or, try triggering raw samples via MIDI without any effects, I bet it nulls consistently.