Where are the collections stored?

Hi, the last Pocketbook Cloud update is stuck and I've had to terminate it after one hour or so by turning off the WiFi and restarting my Touch HD3.
But I've lost my collections and bookmarks that are still available on another PB ereader. I've logged off PB Cloud and I'd like to manually copy my saved collections back to my HD3.
Any clue? TIA.