You aren't listening? We are talking at Pentecost BEFORE the people were saved. How did they have the gift of interpretation before they were saved? Answer: they were and they didn't.
They heard in their language because TONGUES is about people understanding in earthly languages.
No - you are blinded to truth by your opposition to Pentecost.
A crowd of thousands milling about the streets of Jerusalem are not going to hear clearly a dozen different languages spoken by 120 people all at the same time.
People cannot distinguish what is being said if there are a few competing voices speaking the same language at the same time in a gathering.
As for you inference that God did not operate the gift of interpretation that is simply your prejudice.
The events of Pentecost demonstrate the gift of interpretation - a gift that would continue to operate when the church came together in number.
Acts 19:6 And when Paul had laid hands upon them, the Holy Spirit came on them; and
they spake with tongues, and prophesied.
Here again scripture teaches us the truth that the infilling or baptism of the Holy Spirit is accompanied by the sign [evidence] of speaking in tongues.
Note also that there was no audience of Jews or others for this expression of tongues to hear.
James 3:5 Thus the tongue also is a little member, and boasteth great things. Lo, how much wood is kindled by how small a fire!
6 And the tongue is a fire: the world of iniquity among our members is the tongue, which defileth the whole body, and setteth on fire the path of nature, and is set on fire by geenna.
Here James explains to us all why God gives the newborn convert a pure spiritual tongue in which to praise and pray to Him without the corruption of our carnal nature.
1Cor 12:3 Wherefore I make known to you, that no one speaking by God’s Spirit saith, Jesus is anathema; and no one can say, Jesus is Lord, but by the Holy Spirit.
1Cor 14:2 For who speaketh in a tongue speaketh not to men, but to God; for no one heareth; but in spirit he speaketh mysteries.