So I've just tried the game with the Complete mod installed, but i didn't expect enemies spawning right behind me, or even front of me.... Just at the end of the first "map" in the building, and even at the start of the second, behind the gates. Hell i can't even grab the loot after killing them..
Is that still supposed to be like that? I mean, let them spawn, but like not within 5 meters around me... Or maybe should I be looking for some more mod, or unofficial fix?

Hmm... I don't recall that ever being an issue for me, either with vanilla, ZRP, or Complete. I believe there's a little quirk the STALKER games sometimes have, where they will suddenly load a bunch of enemies at one time, and they will appear out of thin air. Maybe that's the issue?

I've had this with a few mods - once i went to the garbage from cordon, and spawned right in the middle of a twenty strong military patrol.
One option on another mod allowed "faction wars" where each area would have different factions spawning - the monolith might invade from the north for instance and overrun as far as cordon. the problem was they were spawning constantly. whilst that mod has a simple "switch" mechanic in one of the scripts, the problem was somewhere in the spawn script and required some trial and error tweaking to get it working properly, so i just turned it off.
have a look in the scripts folder of the mod and see if theres one for options within the mod!