fantasy - Showing the transition of language comprehension change

This is a followup question to What language shall they sing in?

I'm writing a middle-grade novel in English with time-traveling kids from 1995 America who go to Ancient Egypt to join the Exodus. My big handwave is that there is a magical invisible Universal Translator (a la Doctor Who).

In the other question I asked about using a song with Hebrew lyrics even though the kids only speak English. I got the suggestion to show the UT as if it were a training tool. Instead of the kids always speaking and hearing English (whether the actual language is English or Hebrew), have them start off only hearing the English but, after a while, they start hearing the Hebrew and realize they can speak it too. Fluently (in accordance with their English skills, which vary by age).

I love the idea and decided to incorporate it. But I'm having a bit of trouble with the execution. I don't want to ask for a rewrite, as that is off topic for Writing.SE, but I'm including a excerpt from the relevant chapter for context.

After dinner had been cleared away, Miriam, Elisheba, and Jemina began to dance. Timbres in their hands, strings of bells on their ankles, they moved in slow circles in an open part of the courtyard. At their center was Jochebed, on a stool, tapping on a drum that rose from the ground to between her knees.

Rah lifting their hands high, hah stepping in a full turn, mah hands lowered, nah stepping forward.

...

The circle began to expand.

Rachamana d’aney

“It sounds so funny,” Melissa said.

Susanna’s eyes opened wide. “It’s not English.”

“Of course it’s not English,” Melissa told her. “We’re in—”

“No, no. Listen.” Susanna lifted up to her knees. “Rachamana. We were only hearing English before but they were actually talking Canaanite. The old Hebrew. Now we can hear what it really is.”

Rachamana d’aney 
D’aney la’aniyey 
Aneyna!

“You’re right,” Phoebe said. “I hear the words but I can understand them too.”

O Merciful One, who answers those in need, answer us!

Notes:

• The highlighted lines are italicized and indented in my text, but I can't manage to get SE to do that.


• I removed half a page after the 2nd paragraph for brevity.


• As the chapter continues, I no longer speak of the language issue but just alternate Hebrew and English translation with description of the scene in-between.


• The discovery that they can understand the local language comes up in an earlier chapter and those kids (Susanna and others not present here) called it a Universal Translator, a term used (by sci-fi geeks) in 1995 thanks to The Doctor.

How can I show the transition between hearing everything as English and realizing you are hearing the other language and you understand it? My goal is to be brief and clear.