1) As a workaround, I can join image by choosing "File" (default picker) and not "Image" in dialog.
But this "File" choice picker is not available for task ! Look screenshot, not the same dialog between event and task, no Drive for example...
2) Other problem, when I share picture to Calengoo, I can choose between Local and Drive.
If I choose local, Calengoo crash.
3) When I join file, filename display empty area in event, and if I tap on it, dial is display.
4) If I join file to event and look this event in an other device, there is a red triangle (because file not exist in this device).
If I tap this triangle, there is toast error. Maybe you can customize it to be more understandable "This file do not exist".
5) Please add this to translation website
6) really sorry to report so many things. But I love calengoo and I want to have the best calendar app.