He has worked mostly in cities, crowded areas, and from higher points. So he has good eyes at least. Thanks to spotting people through crowds. But a forest is new ground to him. And the highest he can get is on a tree.
Not much to know about him. He doesn’t really have much of any character. His best eye spotting feats is making a sharp enough shot to shoot someone holding another person and shooting skydiving people (and eventually missiles I think. Not sure on that one tho). And shooting while there is a crowd.
I mean... Celeste is an intergalactic bounty hunter and would probably outskill the Sniper by a fair amount. She also fought her way out of being trapped in a spaceship when she was vastly outnumbered and outgunned. Plus, you'd assume that Celeste's advanced alien ray guns would be a little more powerful than normal human guns, which would negate the surviving being shot thing.
That mission, from memory of the game, involved prisoners running away from you, you have a machine gun, and you just unload on them. Not huge skill there.
Celeste fought her way out of prison, and slaughtered an entire ship, all of whom have guns that could presumably one-shot her, given her durability. You can meet her on that day, and she isn't even wounded.