I’m not sure, but you’re correct about my set up. I tried to drop the folder path into syncthing but it wouldn’t take.
I need to sync from my desktop Vault to my phone (and now iPad), so I do that with Mobiüs. I then need to sync the Mobiüs folder to my Obsidian vault. This completes the sync without requiring iCloud.
Since setting this up, iCloud has returned to seemingly stable working order. I’m considering defaulting to iCloud again… The two-apps-before-Obsidian routine is kind of a thought-blocker. But it works everytime and is very solid.