Alex and Bill buy new stems and being an engineer Bill lightens his. After a couple of months of daily rides Bill's twin Ben is convinced and buys the same stem and does the identical mod. Another two months go by and Ben face plants when his stem snaps only to be told "You must have screwed up your mod, ours are rock solid". What's really happened is that Ben's identical stem had a 40% chance of snapping and has done, while Bill's stem used twice as long had a 2 in 3 chance but hasn't. The mod increased the original failure rate of 0.0001 per ride 80 fold but Bill's stem continues to perform the same as Alex's, building up confidence, and there remains a 5% chance he'll still be singing its praises a year later (1-(1-P)^n).
Most of us can't test for go/no-go failures at a meaningful scale and what testing we can do doesn't guarantee repeatability, it mainly reveals any gross weakness. Batteries too have a brittle (exponential) failure mode with a potentially nasty outcome that makes this infeasible testing essential. So the take home for the most part has to be Don't abuse your battery.
Equally it's obvious battery safety isn't keeping up with modern cells and that embedding today's designs into standards to meet commercial ends won't help *. Threads like this, the folk who admin and sponsor the forum despite some iffy posts, the parts access and the enquiring minds to push the limits occasionally, are all essential - trace how mobiles and the internet got here and you can see why. Oops, tangent.
I'm sure you're right about the reason for the weak controller and I get as confident as the next guy in the stuff I build. However if a mod could carry this type of unquantifiable risk to others the engineer in me can't properly refute that, and the responsible thing is to keep any risk to myself regardless of how I feel, hence "Remain cautious with it". I hope you'll do loads more like this but come to see the battery as a special case for most mortals.
(*) At least 18% of ebike fires in 2023 were in manufactured ebikes according to
Govt analysis.