Hue lights show 'On' when in fact unreachable

what surprises me somewhat is that when a hue-light is "reachable": false (because power is cut-off eg) it still shows as On:

12
{ "state": { "on": true, "bri": 146, "hue": 8418, "sat": 140, "effect": "none", "xy": [ 0.4573, 0.41 ], "ct": 366, "alert": "none", "colormode": "ct", "mode": "homeautomation", "reachable": false }, "swupdate": { "state": "noupdates", "lastinstall": "2018-04-16T19:34:56" }, "type": "Extended color light", "name": "Driveway", "modelid": "LCT015", "manufacturername": "Philips", "productname": "Hue color lamp", "capabilities": { "certified": true, "control": { "mindimlevel": 1000, "maxlumen": 806, "colorgamuttype": "C", "colorgamut": [ [ 0.6915, 0.3083 ], [ 0.17, 0.7 ], [ 0.1532, 0.0475 ] ], "ct": { "min": 153, "max": 500 } }, 

can we and if yes how, template this to only show being On when if fact true? Or make the reachabel-distinction.

I ask because i have several outside bulbs switched on/off through a dedicated outside lux-sensor. This simply cuts power when light is sufficient, but the Hue lights stay On in the HA interface. In the dedicated Hue app the light also shows as On, but has the Not Reachable notification.

Made a rest binary sensor for reachability, so that might be used, but i am not sure how i can do that for changing the icons and state in HA frontend:

sensor:

46

light:

54

group:

03

search: how to show state/icon taking into account to the reachability.