I'm guessing these:
https://wiki.esoui.com/Events#UI_Reticle
Combined with calls to functions starting at "DoesUnitExist" in the API article that contain the unitTag parameter, which can be set to 'reticleover' would get you a decent amount of info.
The latter portion of your question seems to be a separate question pertaining to pulling data from some database rather than looking directly at the targets? No.
I've been up way too late so I can't be bothered to test this, but even if it's not quite right it should give you something to work off of:
Lua Code:
function TargetFunc(eventCode)
d(GetUnitDisplayName('reticleover'))
end
EVENT_MANAGER:RegisterForEvent(AddonName, EVENT_RETICLE_TARGET_CHANGED , TargetFunc)