And now we've got a new Manga volume to do!
First up, we have A Sweet Reward (no obvious POV character... unless we count the pound cakes). I think this is the dinner after the Harspiel lesson:
"In celebration of your efforts, I will instruct my chefs to make desserts for all of the Ehrenfest first-years tonight," I announced.
So in both Manga and LN, it looks like it belongs after the chapter History, Geography, and Music.
Then we have Leonore's Out of My Lady's Sight, which happens the day before the Library registration trip. For the Manga, I think this puts it after Mana Compression and an Invitation. For the LN, after The Fourth Step of Mana Compression. In both cases, making it the chapter immediately preceding the library registrations.
Edit: Correction - I forgot the second half of the chapter. That is set after the party return from the Library, meaning its LN placement is actually after Schwartz and Weiss, and its manga placement... well, its definitely after Library Registration, but might be after the first chapter in P4V4, too.