Why are you against the 30 kWh BMS updates? Aren't they supposed to fix the incorrect range calculation and a number of users report success? The worst outcome I've seen is that the update had no effect and didn't improve the range. Is this accurate?
Here is my reasoning: if a Leaf has had that update, then it may or may not
have additional range as indicated by the BMS readings using LeafSpy and capacity bars - you just don't know without a long range test. OTOH, if the car shows 12 bars and SOH without
having had the update, then all you have to worry about is a BMS reset if the SOH is really high. I'd choose having just one well-known issue to worry about, instead of one known and one not yet fully understood.
Someone posted a link, IIRC in the 30kwh pack topic, but it may be the one you mention. By "official" I didn't mean that Nissan had announced anything about it, although they may have, for all I know. I just meant a web report at least based on real info - actual cars with failing modules.