I have not found a way yet to get a log file for events. It would be great to get this especially if you have more complex scenarios (multiple motions sensors and switches) which are in some dependencies.
This is an interesting feature request, however it would be very hard to implement this. The Philips Hue bridge and IKEA gateway do not have a log so it is not possible for an app to read this. This is something Philips Hue / IKEA would need to implement in their bridge. What type of bridge are you using?
Hue and SmartThings