Only Reservations that are linked to a Dimension using a Dimension Field will be synced.
When syncing too and from Google Calendar, only Dimension Fields will be considered. Any links between Reservations and Dimension sObjects using Dimension Junctions will not be considered when syncing.
Google resources can’t be the primary calendar for a synced Reservation.
If you create Sync Connections for Google resources, they will only work when added to a Reservation as an Attendee, not as a primary connection. To make sure the resource is not the primary sync connection, make sure the Sync Priority on the fields is configured so the resource fields have lower priority.