My parents were married for 25 years then publicly renewed their vows during a Mass and 4 years later they got divorced and the following year (year 30 of marriage) they were granted an annullment based on immaturity of my mother who was "too young to fully understand" (19 at the time) all that marriage entailed. Wouldn't the renewing of their vows on their 25th anniversary "override" that concept?
The obtaining of an annulment in the Catholic Church means that it has been proven that an essential element for the validity of the marriage ceremony was lacking. In this case, it was your mother’s maturity. The renewal of marriage vows at an anniversary of a marriage is merely symbolic and is not a sacrament. For your parents to have entered into a valid marriage at that point would have necessitated the preparation that is required of anyone who desires this sacrament. This was clearly not the case with your parents’ renewal of vows. At the time of the renewal it was assumed that the marriage was valid. Besides, the Church does not allow one to attempt to repeat the sacrament of Matrimony when the couple is already validly married.
Fr. Vincent Serpa, O.P.