I thought I'd check your test case in the Github test project. Even though I wasn't able to get your 'object Object' in my Chrome, I did manage to stumble on to some issues with the date/time format setup. I'm working on a fix right now, but until that's released try this:
Make sure the CustomTimeFormat isn't set if you use View specific time formats, and the other way around. This should hopefully cover you for now!
If I recall correctly the calendar widets uses lower case for hours, in an older version of the calendar widget I was able to use the custom expression hh:mm
The message: "object Object" is probably caused by an exception. If you open the developer tools (chrome), in the console tab there should be a bit more info about the error?