Thanks for the huge feedback, very helpful to get a detailed review like that. Helps to improve yourself as a developer/designer!
To be honest about the y position teleporting. The main problem with it is, is that it's super susceptible to human error like you already noticed with wrong warping and stuff like that. So you gotta watch out there, except that, good luck with it!!
Yes! We used cinemachine to setup the camera . There is a handy command you can use: OnTargetObjectWarped() (https://docs.unity3d.com/Packages/com.unity.cinemachine@2.3/api/Cinemachine.Cine...), basically you just have to give the camera the vector3 where the target warped and you should be fine! Also we only used one confiner object with it and just teleported it with the player.
Glad you enjoyed our game! c: