It's a safe bet that these girls will be playing Irish traditional (and maybe Scots-Irish!), and fast enough that the precision of the internal tuning won't matter a damn.

Generations are easier that Clarke Sweetones to tune against other instruments, as described above. Of course it is impossible to see mention of Generation without the accompanying cant dogma that quality control is poor. But nowadays you would be very unlucky to get a bad one, and if you do, take it back. Notwithstanding R&W Rabbit's pout-down, cheap whistles (Sweetones included) are serious instruments. Good enough to have taken many top players all the way.

On this occasion recorders don't come into it.