Links please
This is related to SystemUI Mod, So it's not a bug in this Mod .
afraid I've uninstalled so not able to provide screenshots ... but for calendar, what happens is when you click on a calendar item to edit it, the background remains stock-white but text has also changed to white, so basically no text is visible
for contacts, when you click on a contact item to edit it, the background is now dark, but the header text (e.g. Nickname, IM, etc.) are still in stock-black text and so not visible