The experience of religious visions, those supposedly involving the mother of Jesus or otherwise, is extremely difficult to assess. As far as I know, they cannot be analyzed in a laboratory using scientific means because they are spontaneous and take place without warning. They cannot be called forth upon command.
So far as I know, the only 'proof' of such events happening is the testimony of individuals who claim to have witnessed a religious vision. There is no tangible, physical evidence to examine.
One can debate the legitimacy of blind faith, but ultimately it seems that we as individuals can either choose to believe or disbelieve in something that, at this point in time, cannot be proven to have definitely taken place.