From what I can see (and I could be wrong), I think the values are currently recorded within the App's data, so I don't believe these could be referenced in a dashboard tile. One option may be to record the time as a state value in the light device and use something like @thebearmay's app to produce a tile with the results displayed. My only concern if you did go down that route would be the potential "chattyness" of writing values so often to multiple devices, perhaps a 1 minute poll would be acceptable.
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