I've already had versions of this conversation with Robert and Jonah in person, but I'll reiterate a few things I shared with them here, since you asked politely. Also, this conversation is becoming aversive to me, so it will become increasingly difficult for me to respond to your comments as we get farther and farther down this comment chain.

specific examples of times when Jonah's explanations were too abstract and not sufficiently practical?

There were actually multiple times during the first couple weeks when I (or my partner and I) would spend 4+ hours trying to fix one particular line of code, and Jonah would give big-picture answers about e.g. how linear regression worked in theory, when what I'd asked for were specific suggestions on how to fix that line of code. This led me to giving up on asking Jonah for help after long enough.

what are some specific topics that you think were neglected in favor of more abstract but less applicable material?

Intermediate and advanced SQL, practice of certain social skills (e.g. handshakes, being interested in your interviewer, and other interview-relevant social skills), and possibly nonlinear models.