But just now when macOS notified me that a feed refresh had occurred, I accidentally spotted a minor anomaly in the status bar (at the very bottom of the Main Window)

It should read 'Refresh completed' as I recall from my previous Vienna version.
The message persists through browsing updated feeds and closing and opening the Vienna Main Window, but disappears after a restart.
On app launch, the status bar shows a live updated countdown of the number of feeds that are accessed and finishes with 'Refresh completed'.
macOS 10.9.5, Vienna 3.5.0