War-wing Siren has the Heroic ability:

Whenever you cast a spell that targets War-Wing Siren, put a +1/+1 counter on War-Wing Siren.

Captain Of the Watch states:

"Other Soldier creatures you control get +1/+1 and have vigilance."

With Siren in play under my control, I cast Captain Of Watch. The Captain has an effect on Siren: +1/+1 and vigilance. Does this count as casting a spell that targets Siren? Should Siren get a +1/+1 counter?

I see "Target" to mean the recipient of some spell or effect.

War-wing Siren has the Heroic ability:

Whenever you cast a spell that targets War-Wing Siren, put a +1/+1 counter on War-Wing Siren.

Captain Of the Watch states:

"Other Soldier creatures you control get +1/+1 and have vigilance."

With Siren in play under my control, I cast Captain Of Watch. The Captain has an effect on Siren: +1/+1 and vigilance. Does this count as casting a spell that targets Siren? Should Siren get a +1/+1 counter?

I see "Target" to mean the recipient of some spell or effect.

War-wing siren Heroic - Whenever you cast a spell that targets War-Wing Siren, put a +1/+1 counter on War-Wing Siren.

Captain Of the watch Vigilance (Attacking doesn't cause this creature to tap.) Other Soldier creatures you control get +1/+1 and have vigilance. When Captain of the Watch enters the battlefield, put three 1/1 white Soldier creature tokens onto the battlefield.

With Siren in play Capt Of Watch is cast. Capt has effect on Siren +1/+1 vigilance. Does this count as casting a spell that targets Siren? Should Siren get additional +1/+1 counter?

Target; the recipient of some spell or effect.

War-wing Siren has the Heroic ability:

Whenever you cast a spell that targets War-Wing Siren, put a +1/+1 counter on War-Wing Siren.

Captain Of the Watch states:

"Other Soldier creatures you control get +1/+1 and have vigilance."

With Siren in play under my control, I cast Captain Of Watch. The Captain has an effect on Siren: +1/+1 and vigilance. Does this count as casting a spell that targets Siren? Should Siren get a +1/+1 counter?

I see "Target" to mean the recipient of some spell or effect.