In the macOS version of Pocket Informant the calendar colors and the weekday/weekend colors are customizeable. This feature allows users to set almost infinite shades of colors to the items.

This feature makes identifying calendars, events weekdays and weekends very easy and quick in the various application views. This all works great until a user switches their macOS from dark mode to light mode. Then what looked terrific in one mode looks pretty bad or almost invisble in the opposite mode and the need arises for the users to manually reset their colors for the mode in use.

This is done manually because it is truly impossible to determine what custom colors from one mode would be acceptable to a user when the Mac is shifted to the opposite mode.

For example the shade of blue a user chooses for a calendar may make the events very easy to read in light mode and they look great, in dark mode that same shade of blue could be very dark and to one user it would be hard to read while to another user the same shade is just fine.

For Pocket Informant it could never make the right adjustment to the color to satisfy all users due to the custom nature of the colors.

So for that reason resetting the colors is up to the user when they change their Mac from light to dark mode or vice versa.