When Twilight Reveler moves to an open battlefield does it count as attacking for her ability?

No. Moving Twilight Reveler to an open battlefield is a non-combat Showdown — she never gains the Attacker designation, so "When I attack" doesn't trigger (FAQ #8664, Rule 383.4.e).

If an opponent later moves a unit into that battlefield during the Showdown, combat begins, she becomes the attacker, and her ability fires then.