No. Basilica Screecher will no longer be on the battlefield when the spell becomes cast, so its ability will not trigger.
Casting a spell:
Only once all of the above has happened is the spell cast, so only then would abilities that trigger on casting the spell trigger.
However, you sacrificed Basilica Screecher back in step 5 (601.2g), so it's no longer on the battlefield when you completed the casting of the spell, meaning its ability will not trigger.