In other words, they have learned the words as spoken, not sung, then just sing the syllables to the tune and understand what they are supposed to mean. That is, alas, no different from learning the meaning of the words and then scatting the song. Sing "tra la la" and know that it is supposed to mean "Jesus Loves You".
See it as you wish.
I was blessed in many worship services wherein such songs also blessed many Chinese because they knew what the words meant in that spiritual and particular song context.
I wouldn't pretend that they'd gotten your permission to be blessed ahead of time.