This is the most fragile kind of Zigbee network, since there is only one path between coordinator and each end device, making it very vulnerable. To create a robust mesh you should have a lot of routers, so there are many different routes for messages to take. The routes used change all the time in response to traffic and conditions.
Yes, it is. Files in it are also json, so you can view them but not edit them.
The delay is probably because of the way Zigbee works. The coordinator doesn’t poll sensors, it waits for them to report. Sensors do this when something changes, but otherwise only check in at set intervals. In a motion sensor, for example, you might also have sensors for temperature, light level and battery level. In an unoccupied room, temperature and light may report every few minutes; battery only a couple of times a day.
When you restart HA battery-powered devices will all show as “unknown” to start with while the coordinator waits for one of the associated sensors to report - and it may take half an hour or so for every device to check in.
Once a battery-powered device has been contacted, if no further messages are received ZHA will wait for six hours before before reporting it as “unavailable”. During this time the states it is reporting will not change.
You may be making things unnecessarily complicated. Zigbee is designed to be a bit of a black box and monitoring can be a rabbit hole as the network configuration changes all the time. Get some more routers.
Several hours reading here, but all very useful. 