Whoever wrote the article is just playing semantic games.
A miracle is by definition;
'an extraordinary and welcome event that is not explicable by natural or scientific laws and is therefore attributed to a divine agency.
"the miracle of rising from the grave"' 1
1
https://g.co/kgs/uNMefQ
By comparison your article defines miracle as, 'Miracles are not seen in Islam as unnatural occurrences, but as natural phenomena that are concealed from human knowledge at that period of time.'
But natural phenomena are explainable by natural laws, even if the explanation is not currently known. So it seems like a misuse of the word miracle to apply it in a religious context to a natural event.
Additionally your article seems to apply this to the Virgin birth of Jesus. Which is odd because the Qur'an seems to imply that it was the result of divine intervention.
'The similitude of Jesus before Allah is as that of Adam; He created him from dust, then said to him: "Be". And he was.'
'She said: "O my Lord! How shall I have a son when no man hath touched me?" He said: "Even so: Allah createth what He willeth: When He hath decreed a plan, He but saith to it, 'Be,' and it is!'