There is a great Scripture explaining the language skills in this situation.
6 Then said they unto him, Say now Shibboleth: and he said Sibboleth: for he could not frame to pronounce it right. Then they took him, and slew him at the passages of Jordan: and there fell at that time of the Ephraimites forty and two thousand.
(Judges 12:6)
I’m still working on “framing” the phrase Mālō e lelei correctly. For a language that has only 17 letters in the alphabet you’d think it would be a bit easier to learn.
It is a great joy and privilege to listen to them sing!