Observation: most calendar software I regularly use (the default apps on Mac & iOS; World Time Buddy, & some others) is not great when dealing with events that end past midnight. For example, in WTB I can’t select a range outside the 24h period spanning the “home” time zone; Apple’s apps show the event on the next day as if it was scheduled ON that day (which Calendar Timeline doesn’t do); etc.

I consider this an accessibility problem, where accessibility is defined as “making your software accessible to everyone”.