Seeing that I have to reinstall all the mods again, I was wondering if something needed and could be done about monster spawning in this game, before I start a new game.

I have a Baldur's Gate 4 in 1 box set, which includes both games and their expansions. I really want to play these games for their stories, but the monster spawning ruins them for me. I might have my party wandering in the wilderness, when I encounter and dispose of some bandits. A short while later I encounter a bear, which I decide is too tough for my mostly level 1 party members, and start to head back in order to get around the bear. But the game has decided that after leaving the visual range of my party, it can immediately spawn the bandits again in the same place. This also happens sometimes after loading a game and my party suddenly has an ogre standing next to them.

This is annoying in a game where one shot from a bow can instantly kill the less armored members of the party. I'm not against challenge, so I'd rather not lower the difficulty setting. I just want the challenge to be fair and not to be reminded all the time that this is just a computer game (although it is, but immersion is important for me).

I found a mod for EasyTutu called Spawn Randomizer, which seems to correct this issue. But now I bought Planescape: Torment from GOG.com and I'm wondering if I will experience the same annoyances in this game too. I have already noticed that some thugs in the first city are back after my party has visited a building. Tutu is not available for Ps:T, so I'm looking for a solution, if there is one and if it's really needed.

TLTR: Will I encounter Baldur's Gate I -like mob spawning in Planescape: Torment and is there a way to adjust this?

There's only one actual zone where respawns will be an issue, and that's late-game Curst. However, by that point, you're more than strong enough to deal with the baddies, so there's almost no worry about getting killed. The other zones are just the Hive and its usually-non-hostile thugs mentioned above (which aren't really dangerous to anyone, ever) and Undersigil, which only respawns when you exit the zone.

Oh, there's some respawning in the Outlands and in one of the mazes, too, but that only happens when you reload a save in that area. Those guys aren't really dangerous either.

tl;dr You don't have to worry about anything even CLOSE to the irritation of Kobold Archers in Firewine. Secondly, starting area for PS:T is full of really weak monsters and lots of dialog and quest XP, so you won't have to worry about getting one-shotted by someone at level 1, either.