Apart from the bug that set dates when edited jump to jan 2014 there's a bug that the widget doesn't a refresh when a task gets updated.
Unfortunately, we can't reproduce this issue either. Editing a task shows the changes instantly upon saving them and the app syncs the changes immediately. Please let us know what version of Android you're using.
I did a restart on my phone and everything is fine now. you may close this ticket. sorry for the inconvenience.
kind regards, Pieter