Clearly they have made a determination to keep matters private if the victim wants it to be kept private and I am no expert in Finnish law but if you say that withholding this information on Watchtower's part is a crime then shouldn't it also be a crime for RV from not going to the police themselves as an organization or individual members in compliance with the law.
First, we're talking about Dutch law here, not Finnish.
Dutch law has mandatory reporting only for very severe crimes, such as murder and rape. Unfortunately sexual abuse of minors does not fall in this category (unless the abuse included sexual penetration under threat of violence or blackmail aka rape).
The law on mandatory reporting may be changed to include child abuse though. This a direct result of JW refusing to cooperate with an inquiry.
The law on rape was being revised already anyway; any sexual penetration without consent will be classified as rape. Under current law having sex with a sleeping, drunk or unconscious victim who is incapable of (not) consenting is not considered rape. Under new law it will be.
Anyway, back to mandatory reporting. It appears that if among the 300 cases there's a report of rape, RV would indeed have to report it to the police.
Given that they have already been in contact with a lawyer, and the police, and the DA's office, and the Ministry of Justice, I'm quite sure they have this covered somehow. No doubt at least one of the above informed them of their duties.
And from what I read it may be possible for the DA to exempt someone from mandatory reporting. Perhaps RV was granted an exemption given their function as a trustee to victims?
Or maybe RV has already reported rape cases to the police, and simply doesn't shout it from the rooftops to protect victims?
Anyhow, RV focus is not on whether or not Watchtower committed crimes by not reporting. Their focus is on improving the situation for victims and better prevention (see my previous post)