Display outline only (not solid fill) for pending invites
Same as Google Calendar (both web version and app), have events for which one has been invited but not accepted have a transparent fill and only outline coloured - only accepted invitations or events created by oneself having solid fill: https://imgur.com/ajI8LiH
This is very helpful to identify events where attendance has been confirmed/not, specially in Weekly view.
With several and often overlapping events in my work cal, understanding from the day view which you are attending have declined and not yet rsvp'd is essential to see your days agenda. This for me is the unfortunate missing feature that stops me adopting BC as my main cal app.