Script Error 200 is a a Script Sequence Breakage due to many outside reasons and the intricacies of the already beefy scripts.txt from Vanilla Brytenwalda. These errors are usually fixed by a quick exit and relaunch of the Mod. Pest Lords can remain up to a month before choosing other factions, specially if their King/Nobles with a modest amount of troops remains in the Map, in that case, they will remain lingering until you hunt them down personally or they all lose troops to attrition mechanics, where they slowly bleed troops until only the leading noble remains THEN, the switching side script mechanic triggers. This is a vanilla mechanic. Also what you describe as a wounded garrison is pretty odd, never seen it before. Is this with a fresh standalone install?

I've been having a strange thing happen in battles. Every time I raid a caravan the last man that tries to route keeps teleporting back into the fight. Then he teleports around the map and swings his weapon and damages my men. Sometimes he will even kill them. After doing this for about 5 minutes he teleports to my blob of men and gets taken down.

Tried to replicate the wounded garrison bug with 1.05 on the same savegame. Just normally waiting outside the castle and holding space didn't seem to trigger it. Got bored after a while and started spamming ctrl + space (outside the castle) and I think I triggered it once, because the battle (448 vs 1200~) didn't even last a single second.

When I originally posted about that, I was using 1.02 and waiting inside the castle.

Script error 200 all day on the old save but it doesn't seem to happen with a new save, yet.

If it happens a lot with an old save then probably the save is corrupted. This happens frequently for some people and once a savegame has been corrupted there is not much you can do. I am glad that with a brand new savegame error hasnt happened yet. As a rule of thumb get used to saving manually instead of using autosave/quicksave. Quicksaving is from my experience the main root of most corrupted savegames, specially if you manage to quicksave at the wrong time (script running a long complex sequence, lots of things happening in front of you, after a big fight etc) This is a Vanilla Warband issue only made worse by the complexity of Brytenwalda (the script file is very big)