Hi, I would like to retreat my statement that Huawei Optixstar HG8145X6-10 not implementing 802.11k/v/r protocol.
My previous test showed that my device didn't switch between SSID from main router and 2nd router due to default setting of the
Cascade Link Threshold value is too low, i.e., 200kbps.
Meaning that if the device's data transfer rate lower than 200kbps then it will switch to another SSID that is stronger.
After I increased the cascade link threshold from 200kbps to 40000kbps, my device able to switch between main router and 2nd mesh unit's SSID seamlessly.

Conclusion is Huawei Optixstar HG8145X6-10 is compliant to Easymesh and able to switch between SSID seamlessly.