I’ve just spent a few hours migrating my notebook from Zim to Joplin.
One thing that would have saved me most of the work would have been to import notes from recursive folders. Now I had to import every folder and subfolder in my notebook separately.
To just select my top folder and have Joplin do the recursive bit would have been swell. Especially since Joplin now supports nested notebooks (yay!).
maybe writing a quick script that would just call the joplin importer recursively on each folder would be better for you, if you didn’t do it all manually already? (I’m not saying it woudl be a bad feature, just giving you a hint in case you’re still struggling with it.)