To answer the original question:
I happened upon Lourdes years ago when I was a teenager in the 80's, homeless in Europe. I ended up there quite by happy accident. I was not a Christian of any kind in those days. I visited the shrine, asked lots of questions and have read a great deal about it over the years because of my personal accidental visit there. Here is what I think, which is what you asked for:
I do not know if Mary appeared to Bernadette, and I plan to ask her about it someday.
Nonetheless, here is what I experienced at Lourdes:
There were a great many people, pushing and shoving. Not out of malice but out of poor desperation. There was a lot of jostling for position at the shrine and many handicapped people were pushed aside. Nonetheless, there were also a great many kind people at the shrine who helped these handicapped, and ill people acheive their efforts to go to the shrine and to pray there.
I did not see anything visionary or miraculous except this: I saw a great many kind, and lovely devout people who assisted the poor, fed the hungry, and held the weak, and ministered to the sick. Whenever I see this, I know I see Jesus.
I am now a baptised Orthodox Christian and of course, I must follow what my church teaches which is mainly that such Marian apparitions are to be heavily questioned and never believed "on faith" but to be investigated thoroughly by theologians, bishops, etc. I cannot say that I believe that Mary appeared to Bernadette. In fact, I have to say that I personally rather doubt it.
As an aside, since I was homeless and suffering a bit myself, I said a little prayer there at the shrine when it FIN ALLY became my turn. My prayer was answered, and I was not even a Christian.
Additionally, the experience weighted heavily on me years later, when I was seriously considering a conversion to Christianity. God can and does use anything and everything to bring us to Himself.
I was baptized into the Orthodox Church and have never looked back or regretted any of my journey, including my visit to Lourdes. All things serve to bring us closer to God, when we allow Him to guide our steps.
But I do believe that God is everywhere, and fills all things, including Lourdes and that of course, He may be present there, and may be working miracles there, in His grace and mercy. Certainly, when we see love in Christian people, we can know that they are "faithful" of some kind and that God is certainly gracious to that. I absolutely know that I saw many handicapped and ill people gently helped to the water, gently bathed, gently and kindly treated by many loving Catholic Christians. Surely, there is a miracle in that in itself, especially considering the state of the world today, since 1917 where nihilism and cynicism rule and apply to every and all situations. There is such a lack of love in any part of the world today, that any act of love is a miracle in itself.
"In the last days, all men will go mad. And when they meet someone who is not mad, they will say 'he is mad! for he is not like us!"
God bless you.