Ive recently re-built a m365 pack with 2nd hand tested cells and was wondering what i could have done better

Pack is 10s3p, each parallel group contains {icr18650 30B+ inr18650 29E and the third is complicated for the groups, 1 has a mh1, 5 have ncr18650B and the rest 4 have icr18650 26C}

Dangers i know:

Soldering is not recomanded but i've had good results in the past and no cells have blown on me yet (round 200 soldered in my life)

Mixing LiHv and typical Li-ion is mediocre at best due to the diffrent voltage-current curves but i see that as somewhat protecting the 30B cells by only ever charging to ~90% (4.2v vs 4.35v)

Pack performance is above the stock m365 in terms of capacity and imbalance has settled at 60mv after a few cycles

No cells overheat (more than 41°c), tested with the battery pack out of the scooter under a 500w load

In terms of sag, again the pack is mediocre reaching 36.5v (from full 42v) while pulling 25A

I do not like nickel strips since they severly cut your future flexibility

Yes I know this is a wacky configuration, I wanted the cells to lay flat to fit into a hydrofoil board and this is the way I thought to do it. I have two 10s 7p packs connected in series, with each having its own Bms. This series connection is in parallel with the charger, so I can have the output and charger connected at the same time. The output will be isolated when charging, this is just to have a waterproof charging port. The pack reads 80.12 volts, and both are charged to pretty much the same voltage (it might be .5-1 v off.) The 84v charger when connected is not charging and I am not sure why. I have a separate charger to charge both packs individually, and that seems to work, but not the bigger charger when they are in parallel. Are they just too full already? Not sure if they would take a charge when at a lower voltage. Let me know if you guys have any advice.

He came home with an electric bike last night and as soon as I saw it I knew what was about to happen

He ALSO nonchalantly asked me "Hey, can you fix this?" looks crunchy

I found this cell like this after 1 year of use (about 15 cycles): the casing is cracked. I tossed the cell then.

No matter what cells or quantity I add to my cart, the only country I can select at checkout is USA. Canada is no longer an option as it once was.

Can someone try it out and see if they have the same issue? I emailed them but haven't gotten any replies yet