Hi, Sen
Theoretically the KW41 Thread BR is not HomeKit device, so it will not accept Homekit Accessory to join its network since the commissioning and pairing stages of Homekit Accessory requires either HW or SW MFI certified messages like credential / provisioning data be exchanged between Homekit Controller and Accessory. The KW41 Thread BR most probably will not provide these mandatory Homekit required information so Homekit Accessory wouldn't join it successfully.
B.R
Patrick