Is there anything wrong with joining a daily SSPX rosary service? I remember reading somewhere that the rosary is more pleasing to the Blessed Mother when said in a group.
The problem is with participating in SSPX activities. While the rosary is an important Catholic devotion and while it is indeed good to pray the rosary with a group, there is no reason for a Catholic to attend a rosary sponsored by the SSPX. Surely there are Catholic parishes recognized by your local diocese that offer rosaries you can attend. I urge you to find one of those. I also recommend that you re-read the answer to this previous question that you submitted.
Ecclesia Dei by John Paul II