For what it is worth. Key repeats as described is a hardware problem. I had the same issue with the letter H. Either duplicates or a random H mid-whatever.

Every single macbook ive owned in the last 3 years has had some defect. Either a dead motherboard. Broken keyboard. Or both. Basically it is build like a piece of shit.

Had I any option I would get a cheaper better faster windows pc in a heartbeat. Sure it'll be 0.5lbs heavier. But by god it won't have that shitty giant touchpad that won't let me type without fucking up my wrists.

https://github.com/aahung/Unshaky

You can set custom timings per key, which is useful for particularly difficult keys.