The 'Sync' link in the settings pane should go to the Firefox Sync account directly when Sync is set up already, instead of going to the Android overview pane 'Accounts and sync'.
sync triage: not a blocker for release or beta at this time.
Android does not allow direct navigation to an Account's subsettings screen via URI. An alternative is to create a screen that mimics a subsettings screen, and embed that within the setup activity. Full integration would require creating several layouts that match each Android version's theming.
I guess it's a WONTFIX then. This can be revisited if a future Android version allows direct navigation.