With thanks to Neil Forster for drawing my attention to this matter.
J.C. and others v Belgium (European Court of Rights) has a media release summary here As explained in the summary:
The case raised the question of the immunity of the Holy See from the jurisdiction of domestic courts.
It concerned in particular an action for compensation brought by 24 applicants against the Holy See and against a number of leaders of the Catholic Church of Belgium and Catholic associations, claiming that damage had been caused by the structurally deficient manner in which the State had dealt with the problem of sexual abuse in the Church.
As the Belgian courts had found that they did not have jurisdiction in respect of the Holy See, the applicants argued that they had been deprived of access to a court and relied on Article 6 § 1 before the European Court of Human Rights.
The Court found that the dismissal of the proceedings by the Belgian courts in declining jurisdiction to hear the tort case brought by the applicants against the Holy See had not departed from the generally recognised principles of international law in matters of State immunity, and the restriction on the right of access to a court could not therefore be regarded as disproportionate to the legitimate aims pursued.