We know that Sonya is Elizabeth, Teresa is Deedee (might actually be a nickname), and that Thomas is Stephen, but none of the others have confirmed legal names. Here are my personal headcanons for what the others are. Only the characters i’m super familiar with, may be updated in the future.
Frypan: James
Newt: Isaac (funny…)
Alby: Alan
Billy: Carson
Minho: Youngjae
Winston: Isaiah
Gally: Levi
Chuck: Tim
Zart: Alexander
Clint: Lucien
Jeff: Dimitri

I think im done let me know what u think I painted him and gave him drool. Also hes not that green thats just lightning hes the color of celery so dont judge him. I also haven't named him yet

They basically ended up where they could end up in second movie except even seemingly worse. They just traded Newt’s life for Minho’s and the only actual difference that was made was causing more deaths and going through very hard time. Like it wasn’t worth at all. Also Tereza died which is bad for Thomas.

Other than that everything they achieved was same as at the end of second movie except the Minho was alive instead of Newt.