“Is it sufficient to sync from a single account for them to be connected? And upon reinstalling the browser, will they all be restored using the sync code?”
For more information on the topic, see here https://support.brave.com/hc/en-us/articles/360021218111-How-do-I-set-up-Sync
@f4p first off, I want you to realize sync isn’t meant to be a backup. It exists only for you to connect multiple devices together. The sync code is set to expire daily. You can read more on that at Sync is not a backup
Each profile is seen as its own device/browser. This means you would have to add each profile to sync separately.