Because the country is a republic the documents regarding Succession signed after 1947 have no relevance.
If only you would apply this logic to the documents containing the old line of succession, abolished in the same year, that have no validity, no relevance and no legality any longer either.
The King, as the head of the Royal House and the Royal Family of Romania, has an important task in ensuring his succession, for the sake of the monarchical cause in the country, and the continuation of the dynasty. In an abolished monarchy, it is the role of the head of the Royal Family to keep the cause going, not just with regards to restoration, but just as important, the preservation of history, property, philanthropic and idealistic causes connected with the Royal Family. It is extremely illogical, provocative and outright ridiculous to keep on suggesting that because he only has daughters, and because his eldest daughter has no children, the Royal Family should look outside the country for an heir to keep furthering the cause of the monarchy.
You cannot claim that one document from 1947 is valid, but another one is not. You equally cannot claim that the Crown Princess has an invalid title, but recognize the King, because it is within his rights to create titles, and you accepted that fully when Nicholas Medforth-Mills was made Prince Nicholas in 2010.
If the King chose not to change the line of succession and ask Parliament to approve it in the case of a restoration, he would not do his job as the Head of a Royal House, and the claim to the throne would die with him someday. He would be criticized by every monarchist for ignoring his responsibilities and not caring about the future, which is the exact opposite of what the Romanian Royal Family stands for.
You're disappointed with almost everything that has to do with Prince Radu. I am disappointed with events surrounding Nicholas M-M. So what? The cause is greater than one person, and the endgame is the future of the Royal Family and the restoration of the monarchy in Romania. That cannot happen without the King making his will clear, which he did in 2007, as did H.S.H the Prince of Hohenzollern, when he made it clear his family had 'no interest in the Romanian throne'.
How do we support the monarchy, the Royal Family and how do we convince our neighbours, our family and our friends to get this issue up on the agenda, and allow the change we want to happen?
It can't be done by trashing the Royal Family at every turn, and then claiming to support the monarchy. It won't be done by dreaming about finding a German Hohenzollern to come to Romania, like they did 150 years ago, and start a new dynasty. It will never happen.
Restarting the monarchy is hard enough, at least try to be realistic about what is doable and not. Otherwise you're just sabotaging the cause, and I'm not sure that's what you really want to do.