Xiaomi milo binding - how to trouble shoot issues with Color item

Sorry for doubt posting - I’d like to get some advice one how to troubleshoot an issue with Color item that controls light with miio binding. I exposed the light to HomeKit via homekit binding, however brightness channel doesn’t work, so it might be a problem in HomeKit binding or the way how miio binding send command to the device. My theory is documented in this post: How to configure HomeKit light with colour? - #32 by yfre
My question is: what can I do to check what command does miio binding send to the light when it only receives changes to brightness?
Many thanks in advance!