Prius V battery swapped from Nimh to Li-on questions...

Hey, i am legit on my wits end here and decided to seek help here.

I've recently (20 days ago) bought a Prius V that was converted to a european 7-seat version. They also removed original nimh battery and installed li-on in the middle. Now, the whole issue starts here. Dealer that important the car from USA and converted it in 2021 went the cheapo way and instead of converting entirely with ECU/BSM/ABS swap, they simply trimmed the battery cables from Li-on harness and somehow made them fit into original Prius V driver that's made to work with Nimh battery.

I bought this car off of a 1st owner that bought this car from this dealer and did 300k km with it apparently with no issue despite this battery setup being an absolute circus. Shortly after purchase i've got hit with P3018 error of block 8, checking on it with Dr Prius showed IE as high as 25 and volt diff while hard braking was as high as 0.8, at the time i didn't have money to replace the battery so i kept driving for next 2 weeks until... well, the entire battery went to hell as the module #8 burned entirely. I towed the car to nearest workshop specialized in swapping these and thats where i got to know what kind of messed up construction this is. They told me they never seen something like this and they can't fully swap the battery because it won't be compatibile with BSM and won't work so best they can do is swap the modules into the "converted" harness and plug it the same way it was, which i said ok because well i didnt have many other choices.

Here's where the issue starts. Same day i picked up the car, Dr. Prius keeps showing me the same worrying signs that were there with previous modules and balance issue on Block #8. Theres no errors right now, but hard braking slams volt diff to 0.75 and IE on that block is 14, while all others sit at 7, basically its as if modules werent changed at all (they were since the old battery died entirely and i got the burned modules back). Mechanic says to ignore Dr. Prius because it won't show correct data due to wrong driver module and to just keep driving which seems completly off to me because Dr. Prius correctly sees 14 blocks, not 26 that nimh has and previously it correctly spotted issues with faulty block #8. I assume the problem here is not with modules but with harness or busbars or some other connectors around block #8 that causes it to take too much energy/give too little and have way higher resistance. Workshop refuses to take it back because "they checked, it was okay" even tho they didn't do any stress-tests, just checked with voltage is correct, slapped it back in and told me to piss off.

I know that in order to get this battery to work properly i should invest into proper BSM/ECU/ABS Pump swaps, but thats too much money for me rn and even tho this construction is an abomination, it worked for so long so i assume it should keep working but... Is it possible that Dr. Prius/Hybrid Assistant are mistaken about new modules working out of order? From what i read even tho driver is wrong and BSM treats this batter as if it was Nimh even tho its Li-on, the data it reads is factual so if it clearly shows me such huge voltage difference it comes from something.

Do i trust the app or do i trust the mechanic and keep using this? I can't afford to degrade those modules again due to overcharge or risk another battery burning down because this fix already cost me 1.1k€. Any advices how to play this out?