My advice: Spend as much time as possible on court with those three. This will boost your overall game more and more sustainably than another 500 posts in here. Also, try to get some singles matches going with them. They will wipe the court with you in the beginning if they go all-in, but this will force you to improve your court coverage, footwork and everything that goes along with it automatically. Just compare your movement and posture in those two clips to the previous ones. Like night and day.
Regarding your smash technique, there is one thing that I still really dislike and which has been discussed a couple of times already - that weird side-to-side oscillation motion when you try to do a scissor kick (watch the legs):
View attachment 191693.
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It gets worse the harder you try to force a hard stroke. You do not generate any momentum or power in direction of the stroke with that and you end up in a bad position to initiate any follow-up movement towards the net. I won't comment on any other aspect of the overhead movement since you have the real BC-experts already around to take care of that way better than I could.
Watching the latest couple of clips, I get the impression that maybe you are forcing it a bit too much and with that, you lose the lightness that is needed. Looking at that first screenshot, I can almost see your white knuckles from squeezing the handle. Try to loosen up a bit and maybe think about reducing the frequency of your video documentaion. IMO it's very, very hard to spot real progress if you don't give yourself a bit of time to internalise some things in between. With the level you have reached now, the learning curve will inevitably get less steep and level out compared to the very beginning.