Apologies if you understand this already but for anyone else reading...
The neighbour lists in 802.11k are requested by the client via a neighbour request (if it supports 802.11k and when and if it feels like it). They are used primarily to narrow down the list of available APs to scan when it is evaluating a handover to another AP - it speeds up the scanning but not the actual handovers. The 802.11r standard shortens the actual handover time - 802.11r is built into the Luci GUI under the Wireless Security tab.
There is nothing built into Openwrt or in the 802.11k standard to handle the construction of neighbour lists.These need to be built by either a AP controller (have a look at the OpenWisp or DAWN - these do not yet support 802.11k) or via discovery using a method like what I have done.
The neighbour lists must contain BSSID, BSSID information, Operating class, channel number. Have a look at https://blogs.cisco.com/wireless/why-the-802-11k-and-neighbor-report-are-important
If you run "ubus call hostapd.wlan0 rrm_nr_get_own" from an Openwrt command prompt you can see the format of the information stored.
If the above script is run and a neighbour list populated you can see the list by running "ubus call hostapd.wlan0 rrm_nr_list"
Change wlan0 to match your wlan interface names.
As for evaluating the performance, you will need to do an on air capture (using an external tool or iwcap on Openwrt) and run it through wireshark, and hope you observe a client requesting the neighbour report from the AP in the pcap file.
802.11v can be used to force a bss transition but will require a controller to manage each client attached to the AP. The DAWN controller implements this based on AP channel utilization.
My script is just a hack to work with a small number of APs (2 in my case) where I don't mind manually editing each version on the different APs.