Even if it were not enforced in code, some guidelines could be valuable. Such as no greater than so-an-so radius for targets including the point of origin, etc. If that is the major cause. Also, the guide is probably not too accurate about the number of targets, as I've used more than 4. A very finicky spell.
Arcane Archer Imbue Arrow Bug: The IA selection will reduce spells available to zero for a level, but when 0 spells are available, it will allow unlimited IAs of that level. Image 1 - the possible spells available to cast Image2 - note that Imbue Arrow ignores that no spells are available and and allows imbued arrows with spells. The character has the Heighten Spell feat, but this bug exists without this feat. Just noting to explain the extra spells in the images.
There are multiple bugs in chain lightning. It seems to be a rather late copy paste job of the call lightning rendering code, and they forgot to adapt certain constants. It still works with more or less a maximum distance of 720 inches for the rendering, and doesn't really account for a maximum length. Pair that with randomness, and it'll sometimes crash and sometimes won't.
PENDING: Magic Vestment: conflicts when applied to both a shield and armor on the same user = it doesn't stack and only applies to one or the other. It also conflicts if either the user's armor and/or shield is enchanted. the spell selection description states 1 hr/lvl and the spell help menu states 1 min/lvl Stacking spells exploit: Haste and Stoneskin. Both these can be cast multiple times to stack. Haste stacks the ABAC bonus and Stoneskin stacks the DR potential from each strike. Correct behavior should probably be recasting the spell and removing the current effect. Less attractive, but also possible is to not allow the cast until the current duration is finished.
Verbonc guards do not go hostile. Attacked a number of guards at a few outside locations, in sight of other guards as well. Also inside the City Hall. Immediately after the attacking character is done, the battle stops and the target is not hostile. Or any bystanders. However, inside the Town Constabulary the guards will go hostile when attacked.
Ran into another spell permanence issue with a summoned Djinni which wouldn't disappear no matter the time passed.
PENDING: 1. Opening Vignette for Neutral Evil. You are to visit Terjon and tell him you burned his church. To me this seemed pretty foolhardy at low level. So I talked briefly with him and came back after finishing up in Hommlet with a higher level party, told him, he attacked, killed him. The quest remains at the accepted state. I guess you are not supposed to really fight him...but the smart evil is to come back when you are capable. 2. Gremlich. The Random encounters where you are supposed to hear the Gremlich scream (empty RE) seems to have lost the scream sound. Now it is empty + quiet, which could be confusing if you didn't know that you'll get 3 or 4? of these empty encounters for that quest. 3. Hickory Branch the Orc Lieutenant is very easy to pull (or maybe it is automatic) into any battle in the N cliffs. Oddly, the nearest group to him does not seem to pull. He's part of the quest's dialog encounters and is supposed to talk, leave, then join the exit ambush. To get to him and talk without pulling him into combat, you have to go around the west side of the trap before attacking the N. Upon exiting the cave and fighting all the squad leaders, there is no dialog. I think there used to be long ago...but can't remember. Perhaps Boonthag forces immediate combat. (see next point) Sgt. Boonthag attacks her fellow ambushers. Probably a faction setting? The Lich did not initiate combat and I had to approach and talk. Not a big deal...but I think it used to be a bit of an auto-dialog + fight ambush, iirc.
This is starting to sound like a pattern in your game hammyh - attack Verbo guards and they don't go hostile, group near the Orc Lieutenant don't go hostile, approach Lich and he don't go hostile... does it feel like there's a pattern, or just a few isolated moments? Also, do any of these characters have the red circle but just not act?
PENDING: Re: Orc Lieutenant pull: I suppose I was not explaining this one well. The Lieutenant is further away than the nearer archers that engage at their maximum range, as well as that other normal troop group. He probably should not be pulled. The other group I referred to behaves correctly, ie. it's just too far away to be sensibly pulled in. The normal troop group is correctly hostile, but does not become hostile 1/2 map away. No idea on this one. For example, I attacked the Hommlett Jeweler, Jaroo, and Burne crew..at night after Terjon (After finishing wotgs). They all pulled nearby creatures into combat and remained hostile. The rest of the entire village didn't instantly go hostile but Hommlet was no longer a safe area and I could no longer rest there. (I did not go back to check if I was eventually KOS. I did get Butcher reputation after Terjon.) The Orc Lieutenant is intended to survive to participate in this scenario (he is in the middle). The ambush group was initially all blue with one red (Ogre) Then there was the infighting with Boonthag, but that only started after combat. Boonthag started out blue/non-hostile. Screen shot of the intial conditions: Isolated. All other encounters on that map forced dialog correctly in visual range: All group leaders (except ambush), cave battle, Minotaur.
Ok, I've seen something similar (though not identical) at times in KotB where the enemies go red but don't attack for a while - sometimes a long while. Different problem though. Thanks for the comprehensive answer.