Not sure about your Face ID issue, but I do remember a post that was having the same sort of problem with restoring True Tone without the original screen on an iPhone XR. Apparently 3uTools wasn't giving the correct number to program into the screen; they found the right one using something called JC Repair Assistant. Here's the post.
[post|754016|iPhone XR true tone not working despite using Qianli iCopy - iPhone XR - iFixit|new_window=true]
Hopefully that'll get you going on the True Tone; I'll have to leave it to others to figure out your Face ID problem.