Hello,
The supported IDEs for the FRDM-KW41z are currently MCUXpresso and IAR.
I tried running the section 10.5, you will see a difference when you send the command thr joiner view:
Documentation:
$thr joiner view
Index EUI PSK
0 0xFFFFFFFFFFFFFFFF kinetis
Actual result:
$thr joiner view
Index EUI PSK
0 0xFFFFFFFFFFFFFFFF THREAD
I attach some screenshots from the process I followed:

REED (Node A)

ED (Node B)
Best Regards,
Estephania