I've enjoyed reading your level-headed posts as well.
The question got me to thinking about how the courts might treat ownership of Catholic lands and buildings in countries like the US. I think there have been a few rare cases where insiders (priests, nuns or lay employees) have sued the Church, and the courts have ruled that, at that boundary where statute crosses over into ecclesiastical law, the cleric or employee is bound by the Church law. I think from that standpoint the courts of the world would agree with you, all such lands and buildings are owned by the Church, and that the Pope is the Chief Executive who rightfully controls them, if only through his designees.
I guess it all boils down to what they do with that wealth. Some folks estimate the wealth of the Vatican at $10B with an annual global outlay of $171B which largely goes to the salaries and health benefits of their estimated 1M employees and clerics. That may seem high, but it's only 1 employee per 1,800 congregants. The US spent some $588B last year on charity, of which the Catholics contributed perhaps 17%, although this probably doesn't include outlay for colleges and universities, hospitals, and orphanages. In any case it's a phenomenal amount of money. They estimate that they serve 10 million poor Americans annually.
It may be that they just aren't at that point where they need to auction off their art treasures, even though the sex abuse payouts were crippling to many local dioceses - around $3B. I suppose as long as they keep them on display for the benefit of art lovers they're applying them for some useful purpose. The other side of this is how they might go about the business of expanding their services when they're already so huge. I think this needs to define them in the future. To that end, they should try to push the envelope, for example, by migrating as many of those 1M employees as possible into direct charity work. I have no idea how much it would help, but it would seem to legitimize the religion in accordance with its own precepts. And they might as well just drop the contraception, abortion and gay issues altogether. Other than that, they are probably the least offensive in terms of meddling with public policy. I don't think they have any claims against climate science, they're not the ones who have been meddling in the school science programs, nor interfering in scientific institutions and agencies, so if they would just stop indoctrinating children I think I they could be among the first religions to become legal under the criteria I was suggesting. I think American Judaism fits that nicely, too, as well as most of the orthodox Protestant churches. The other world religions in the US, as far as I can tell, are innocent of all the political manipulation, and could also be authorized to operate once they did away with their indoctrination programs.
Countering this, in practical terms, is that the US Supreme Court, who would ultimately decide this, are (at present) entirely either Catholics or Jews. That's quite remarkable as a matter of statistics, since the vast majority of American believers are Protestants, and obviously the colleges of law matriculate countless people who share none of the Judeo-Christian beliefs.