In the future, if you plan to add sync, consider reimplementing Joplin sync algorithm
That would give you tens of thousands of passionate users, dedicated FOSS server as well as webdav/s3/dropbox/onedrive client sync ability, webclipper and a lot of support to navigate future issues/roadmap
If you ever decide to do that, there's even a plan to repackage the algorithm as a standalone library
I'm not to much worried about the syntax, KleverNotes follows Common Mark, so as long as the other app follows it too (which it should) this part is okay
I'm more worried about directory structure and things like that, but I'll have to read more about both API before I can really say anything concrete on this subject
By the way, if you have something in Joplin that you really can't live without, let me know, I'm always looking for pottential features :)