I'm not an expert in the field, but the example screenshot in Hubitat's Zigbee log docs show RSSI values quite similar to yours, albeit generally slightly better, and I can only imagine those were taken from the functioning hub of a staff member. Nearly all of your LQIs are excellent. I'm not sure if the RSSI is an indicator of a problem since the docs only tell us that "close to 0 is good" but I don't think actual 0 is possible in the real world, and the docs don't provide any indication as to what acceptable values may be (and they really suggest that the difference could be in either direction, presumably as if the signal would spontaneously amplify...).
In any case, if the only Zigbee devices you have on this network are bulbs, you're likely fine. The issue with bulbs is what was mentioned above, but it's generally described as a problem with bulbs dropping messages from non-bulb devices (I theorize it's because they are meant to work on Zigbee Light Link networks, where the demands are less, but being joined to a Zigbee Home Automation network like Hubitat overwhelms their comparatively limited resources). But I'm not sure an occasional total loss would affect your RSSI, since it seems to me that this value can be calculated only when something is truly received.
But I'm also curious what typical real-world RSSI (and LQI, I guess) values look like. I'm not sure if my mesh is objectively "strong," but I have mostly Zigbee devices. I also have a second Zigbee network (Philips Hue) and my own 2.4 GHz Wi-Fi network, plus who-knows-how-many of my neighbors' networks bleeding into my house. LQI values I see in logs since I've had this post up range from about -51 (Xiaomi temperature/humidity sensor a few feet away from a Tradfri outlet) to -78 (many are around this value, including an ST ADT water sensor sitting on the floor a few feet above an Xbee, my Hampton Bay Fan Controller that is right next to the same Xbee, and an Iris v2 motion sensor in my basement that has to go through either a wood floor or partial brick wall to get to a router). Most of mine are in the -70s. I have a Zigbee router in about every other room. I know some people go all-out and put one or two in every room, but I'm pretty happy with my network as-is, and with a two-story house I think I benefit from having routes available in multiple directions (though I'm surprised the ones just above the Xbee, generally an attractive route according to my scans, don't seem to be as strong as I'd expect). My LQIs are almost always 255, though I see one 250 and 254 in my recent logs.