Evaluating options to strengthen a sparse Zigbee network

That does NOT look good, there does not look to be any mesh networking going on at all. You should add many more Zigbee Router devices. Yeah I going to once again refer you to the read and try to follow the best practice this here → Zigbee networks: how to guide for avoiding interference + optimize using Zigbee Router devices (repeaters/extenders) to get a stable mesh network with best possible range and coverage

FYI, Aqara’s Zigbee devices are infamous for not automatically moving to better/closer Zigbee Router devices on their own, it is well known within the community that you will need to manually re-pair/re-join Aqara devices after you add more Zigbee Router devices.

Most other Zigbee devices revealuate neiboring Zigbee Router devices and usually automatically move around once every 24-hours if there are any better/closer Zigbee devices available.