Probably just different dialects/accents/etc.
Not everyone in an entire country talks the same.
No matter who you get to record the audio, someone will say its strange/wrong.
To give some serious feedback, I think there might be something wrong with the recording environment. Most of the recordings done for newly added words (plus some from levels 51-60 which I’m working through now) have this strange sound to them. Some of them sound echoey or like there’s feedback/vibration in the sound.