Are my passwords on all my devices?
Yes: each change is encrypted on your computer, then copied, still encrypted, to your Cloud, and your other linked devices receive it.
What you need to know
Under the Mon coffre (My vault) title, a sentence tells you where the copy stands: for example « Synchronisé à 21 h 42 » (Synced at 9:42 PM).
Without Internet, it says « Hors ligne : vos changements partiront au retour du réseau » (Offline: your changes will be sent when the network is back): nothing is lost, everything goes out when you’re back online.
Only your linked devices and your recovery sheet can open your vault. No one else, not even GS Informatique.