I don't think they necessarily got this from coptic hymns. I mean, to be honest, I have no way of determining the authenticity of this music as having come from pharaonic texts, but it would be really cool if it did.
Technically, since all ancient Egyptian and Coptic music was transmitted orally and never musically transcribed, Khepra is correct. There is no way to know if any ancient Egyptian hymn survived into Coptic music. But there is a small possibility since there is no contrary evidence to suggest otherwise.
In this particular piece, the composer likely wanted to express artistic license, not historical musical accuracy. So Mina is right too.
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