On or after the validation effective time, unless determined otherwise in an action brought under § 21.914 and subject to § 21.907(e), each defective corporate act ratified in accordance with this subchapter may not be considered void or voidable as a result of the failure of authorization described by the resolutions adopted under Sections 21.903 and 21.904, and the effect shall be retroactive to the time of the defective corporate act.