“Much to my surprise I recently learned they do NOT really monitor each cell “
Tesla monitors every cell. I assume most quality units do also. Don’t know about the cheap Chinese.
BMS limits voltages on individual cells during charging. I understood this where each module was a series of cells but having learned that Tesla uses parallel cells in a module I need more info.
If you get an answer let me know. I know people I could ask but things change so much in the industry its hard to keep up with it and many of them hold stuff close to the vest for a competitive edge.