I am not seeing an issue. When I tap the “+” button I get a view like this:
Form for New row defaulted to Today’s Date and the time right now
These Date/Time defaults are controlled here:
After changing default Date/Times, I see event entries on Calendar like this.
After tapping on the “Test 2” event it opens in a Detail view. The dates and times are showing correctly.
After tapping the Edit button, the Form opens with the existing row and show the correct Dates and Times as previously entered
Where does this go wrong for you?