"Errors" is the subject and head of the sentence. These errors come in two kinds. Some are errors of timing, and the rest are errors in the attitude (position in three-dimensional space: e.g. nose up, nose down, nose to the right etc.) of the spacecraft.
"Map projection" is just a misuse of technical jargon. What the author meant and should have said is map.
A nudge is a gentle push or shove, and the passive verb "to be nudged" has a corresponding meaning.
Student or Learner