How could the crowd hear the, "the wonderful works of God" if they were as yet unsaved and had not been given the Spirit? Notice, they heard "them", not "him". The unsaved crowd wandered over to hear their own dialects. In your paradigm, the lost should be in your assemblies interpreting the babbling for the saved.
**Notice, they heard “them”, not “him”.**
First of all, the ‘mutitude’ consisted of Jews from other nations, that knew at LEAST two languages (obviously, they already knew Hebrew).
Let’s round off the 17 languages to 20.
120 in the upper room. An average of 5 speaking a native language known to a segment of the ‘multitude’. Even though Jerusalem was crowded for the feast, and 3,000 were converted that day, let’s throw out a conservative number that came in to witness the initial outpouring, say 1,000.
So, an average 50 pilgrims (they) heard 5 converts (them) speaking in their native tongue.
The multitude shared with each other (in Hebrew) their amazement of the scene. No interpretations needed.
Even more amazing and may have even been the case: each of the 120 spoke a sentence or more of EACH language. “..every man heard them speak in his own language”. Acts 2:6
Once again, no interpretations needed.