It's just that when I had BPseries installed, I suddenly was confronted with the inventory lag. I never even knew that that was a thing up until this point. Like I said I am not 100% sure about this. I still had the lag without custom NPCs in my party when BPseries was still installed. So it's all a bit wishy-washy on my side, since I wasn't testing it or anything. The mod can be installed. It may cause some issues with users. Maybe keeping the red flag may be the best for this mod. Or add custom warnings and notes. Tho, I don't if you can do that with the BWS.
I did a bit of my own digging as well and found that horred (the BP creator) last provided a patch for the mod in 2014 for *rough* EE compatibility before he retired from modding. This is still used today, however, the EE game has been updated since that patch and that may have impact on compatibility.
meaning the NPC either stands around or does their basic attack*
In deed, the patch is *rough* as it replaces most actions in the scripts with NoAction()...
Ah, that explains a lot.