from what I just read it sounds like the CSD are going to overrule La Liga to allow a 3 month temporary registration while they work on Barcelona's appeal to make a clear long term legal decision
also interesting to note that not only does this decision mean that Barcelona would be breaking the salary cap/registration rule, but Spanish football has a rule that the same player cannot be registered more than once to a club during a season, and this also means they are breaking that rule too.
also, what happens if Olmo has amazing games against Real Madrid and Atletico, scores important goals, wins the games for them, then its ruled that he shouldn't be registered so after 3 months he can't play, and Barcelona win the league by a point or on head to head ? can see other clubs being pretty upset with that
anyway, none of this is actually confrimed yet so the rumours may not be 100% correct