These differing chapter conventions baffle me. I don’t understand why they should be different. I’ll have to speak with a translator. That would be a great conversation.
I’ve read four different English translations of the book and I’m pretty sure all of them follow the chapter conventions of the Maude of the Oxford World’s Classics edition I’m reading now. The only one that doesn’t is the Maude translation of the Norton Critical edition. That book, if I recall correctly, has significantly less chapters because there is a chapter break only when there is a change in scene.
In terms of the ethical commentary I think Pierre should honor his promise to Andrei because Anatole is such a bastard. That is, Pierre will derive more benefit for himself by not hanging out with Anatole than by hanging out with him.