I would love to know the specifics of how the BMS works, but I think you might be right about it only reducing power/locking out the battery based on whole pack voltage. I regularly see my weak cells in the mid 2v range under load while the rest of the pack is in the mid 3v range. About 3.2v should be the low end cutoff. So unless they left in the safety shutoff voltage from the 2014 LFP pack, it really doesn't seem to care about a few cells dropping that low.
I have DC charged the car up to about 90% several times while watching cell voltages, and it seems to derate to keep the highest individual cells under 4.150 volts, dropping from almost the full 50kw down to as low as like 8kw.
I have DC charged the car up to about 90% several times while watching cell voltages, and it seems to derate to keep the highest individual cells under 4.150 volts, dropping from almost the full 50kw down to as low as like 8kw.