Seeing this again, I want to elaborate on #8 further.

I think a less controversial way to implement this is to think of it as a doublejump reset fix. Avoid 3 having to jump 3 or more times for a single airtime doublejump (jump, release, jump, release, jump again close to pressing doublejump, release, doublejump scenario). What the players not want is to instantly doublejump off a ledge.

The rule is simple: If you haven't used a spring or jumped off a floor, you haven't used your jump, so you have to waste that jump first, and then doublejump, as how it is. But what this could fix is having to press jumps while falling to reset your doublejump and #5 where you don't regain your doublejump when landing. So focus on making the second press to be always be a doublejump with springs being an 'autojump' that is the only odd thing out. This keeps everything as close to 'normal' as possible.

So in conclusion: 1st press: Waste the jump (or spring) or press jump once after running off a ledge 2nd press: always a doublejump (unless it was a spring). 3rd press: Never relevant. Rename the whole change to "Generous doublejump reset" instead of advertising for a double jump fix.