I filed these bugs a while ago:
I know @zef is busy with a lot of things, so this is an open question to the community: if someone could give me pointers on how to either solve these bugs, or to make it easier for @zef or others to solve, I'd most appreciate it!
In general, if somebody is an invested user of vim mode (I'm not using it myself, right now) I'd love an "owner" of this dimension of SilverBullet. Likely these issues keep deprioritized (until I have a "Vim moment" again 
).
I'm happy to be that person informally. I can help prioritize and curate the vim work that needs to be done, and with a bit of pointers/guidance, should be able to start contributing code and fixes as well. The major caveat is I currently will work in bursts and spurts just because of other things in life.
One thing to note though: the above all seem to be folding related, not vim related. The second one is arguably vim related, but let me check if it occurs in emacs mode as well.
I'd greatly appreciate this work. I'd love to make 'zooming in' on a single bullet or heading work, and other outliner features too, but good folding seems like a prerequisite.
If you're familiar with the code, would you happen to know if these things can likely be accomplished in Space Lua or a plug, or if outlining features are complex enough to require core changes?
And while I agree that this isn't generally Vim related, vim does have many not-implemented fold actions, e.g.:
zo opens a fold at the cursor.
zO opens all folds at the cursor.
zc close folded text
zm increases the foldlevel by one
(see Vim Commands · GitHub)
At some point a 'vim-owner' could potentially add them. As there don't seem to be default folding hotkeys, I'd be curious what others use.