Edit2: Scoreboard seems to work now. /blockdata to a tnt block does not, but is because it is not a data holder block, which sucks but seems to work as intended.

/execute @a[score_Facing_min=1,score_Facing=1] ~-2 ~ ~-2 scoreboard players set @e[type=Zombie,dx=4,dy=0,dz=0] isSeen 1

is the code i used to set the variable isSeen to 1 if the Zombies are in a specific line in the direction of my sight. I previously had the code with "effect @e[] 2 1 7" instead of "scoreboard players set @e[] is Seen 1" and it worked like a charm. I tried to adapt it to the new scoreboard possibility for entities, to add a simple blinking mechanic to create more realistic weeping angels.

Seems like a player does not have the permission to execute when the command block was not powered by himself. It works if I press the button with the command.

Would be nice for map makers to have the possibility to let command blocks execute the scoreboard command.

(The image attached is how the line of sights work, if you need to understand this)

Edit1: Also it is not possible to execute the /blockdata command as a block of tnt (but maybe I just fail at these commands?)

/execute @e[type=PrimedTnt,score_det_min=1] ~ ~ ~ blockdata ~1 ~ ~ {Fuse:2b}

[07:22:00] Failed to execute 'blockdata ~1 ~ ~ {Fuse:2b}' as Block of TNT