I'm no expert on the relationship between private and public addresses but is it possible for Bitcoin that was transferred to a non-existent public address to be "re-discovered" if a wallet address is created that relates to the previously non-existent public address?
There aren't "non-existent public address". You cannot have "fake" address that are not real. The transfer will not goes since addresses contain built in check
You can send bitcoin to one of the 2^256 address (like burning your coin) and yes maybe some one can "discover" that private key and get access to that fund... but it's a collision likewise impossible in real life since it means guess 1 private key in this number
115,792,089,237,316,195,423,570,985,008,687,907,852,837,564,279,074,904,382,605,163,141,518,161,494,336
If you want go deeper on that argument... have a look here:
https://notyourkeys.org/https://privatekeys.pw/