But I Thought "Age 18 is When All the Magic Things Happen!" And Everything Before That is "Rape" and "Pedophilia"?

Because even early Christians like Epiphanius also said that Mary was around 12-14 when she "married" Joseph who was 90.

"It will not be without interest to recall here, unreliable though they are, the lengthy stories concerning St. Joseph's marriage contained in the apocryphal writings. When forty years of age, Joseph married a woman called Melcha or Escha by some, Salome by others; they lived forty-nine years together and had six children, two daughters and four sons, the youngest of whom was James (the Less, "the Lord's brother"). A year after his wife's death, as the priests announced through Judea that they wished to find in the tribe of Juda a respectable man to espouse **************Mary, then twelve to fourteen years of age. Joseph, who was at the time ninety years old**************, went up to Jerusalem among the candidates; a miracle manifested the choice God had made of Joseph, and two years later the Annunciation took place. These dreams, as St. Jerome styles them, from which many a Christian artist has drawn his inspiration (see, for instance, Raphael's "Espousals of the Virgin"), are void of authority; they nevertheless acquired in the course of ages some popularity; in them some ecclesiastical writers sought the answer to the well-known difficulty arising from the mention in the Gospel of "the Lord's brothers"; from them also popular credulity has, contrary to all probability, as well as to the tradition witnessed by old works of art, retained the belief that St. Joseph was an old man at the time of marriage with the Mother of God."

https://www.newadvent.org/cathen/08504a.htm

Your "source" says the story it tells is unreliable.

Chapter 8: Mary Turns Twelve

(1) And her parents went down, marveling and praising and glorifying the Lord God that the child hadn’t turned back. And Mary was in the Temple of the Lord. She was nurtured like a dove, and received food from the hand of an angel.

(2) ********************And when she became twelve years old, there was a council of the priests, saying, “Look, Mary has been in the Temple of the Lord twelve years********************. What should we do about her so that she won’t pollute the sanctuary of the Lord our God?” And they said to the chief priest, “You stand at the altar of the Lord. Go in and pray about her, and if the Lord God reveals anything to you, we’ll do it.”

(3) And the chief priest went in, taking the robe with twelve bells into the Holy of Holies, and prayed about her. And look! An angel of the Lord stood nearby, saying, “Zechariah, Zechariah, go out and assemble the widowers of the people, and let them each bear a staff. And whomever the Lord God points out with a sign, she’ll be his wife.”

And the heralds went down through the whole surrounding area of Judea, and sounded the trumpet of the Lord. And look! All the men rushed in.

Chapter 9: Joseph Protects Mary

(1) And Joseph threw down his axe, and went to their meeting. And when they had all gathered, they went to the priest with their staffs. And having taken all their staffs, he went into the Temple and prayed. And when he had finished the prayer, he took the staffs, went out, and gave them back. But there wasn’t a sign among them. And Joseph took his staff last, and look! A dove went from the staff, and flew upon Joseph’s head. And the priest said to Joseph, “You’ve been chosen to welcome the virgin of the Lord into your own care.”

(2) ***********************But Joseph refused, saying, “I have sons and am an old man, but she’s young. I won’t be a laughingstock among the people of Israel.”*********************

And the priest said, “Joseph, fear the Lord your God, and remember what God did to Dathan, Abiron, and Kore; how the earth opened and swallowed them all because of their rebellion. And now fear, Joseph, so that these things won’t happen in your house.”

(3) And being afraid, Joseph welcomed her into his care, and said to her, “Mary, I’ve taken you from the Temple of the Lord, and now I bring you to my house. I’m going away to build houses, but I’ll come back to you. The Lord will protect you."

https://www.gospels.net/infancyjames

And one more thing, "we don't know their age!" =/= "they didn't have an age!"

No early Christian sources say Mary was like 25 and Joseph was 30. There is also book titled "History of Joseph the Carpenter" where people say it mentions their same ages as mentioned in the Gospel of James but I haven't read it personally.