Okay so I finally played through your custom story and I gotta say I liked it a lot. It had the feel of a world where people are living in, which was further enhanced by the voice acting of the guards. The music was fantastic and it didn't have jump scares so I was a happy bunny.
Unfortunately, it was not without its faults. My biggest problem with the mod was the audio. The volume levels were so off that the background music ended up drowning the conversations most of the time, which is a shame considering how enjoyable some of them were to listen to. Simply tweaking down the music could have helped a lot but I also would have liked subtitles because there was a lot of whispering and murmur in the dialogue. Not necessarily a bad thing but because of the music I couldn't even hear half of it.
Another thing that I'm not a fan of is the camera forcing you to look in a certain direction. I don't mind turning the player's attention to a guard or a sound but after that you shouldn't lock their vision in one place for longer than a second. Just because I'm not looking doesn't mean I'm not listening and I like to glance around or have the option to leave if I feel like it. This gives the player the feeling that they're still playing and in control rather than watching a cutscene every time a conversation pops up between side characters.
These were actually the mod's strong point and you clearly put your heart and soul into the guard conversations and I enjoyed them immensely. Although a little more variety could have made them even more excellent, seeing as you had other voice actors at your disposal who could have voiced more of the guards and pagans as well. However, you still brought to life the otherwise rigid looking guards.
You could really do with an animated guard model to be used in place of the regular monster (hint, hint, nudge, nudge all modelers). Because they were immobile they couldn't react to thrown boxes and barrels and you had to resort to invisible walls to obstruct the player from going where the guards would see him. This is perfectly understandable given the limits of the engine and your resources, however, I think it would have been less immersion breaking to have some sort of indication, like a message pop up on screen, to let the player know the reason he cannot proceed that way. For instance, you could have "I cannot go there without the guard seeing me." or "That place is too crowded to pass through unseen." etc.
Concerning the messages and informing the player of what is going on I thought that the mementos could have been made use of in some cases where after overhearing a conversation it would make a note of it. The problem lies of course in the implementation of this because you have to make sure the player doesn't wander off during a conversation and then make a note of it anyway without even hearing it. Naming doors "Home", "Sewers", "Apartment", "Tavern", etc. and letting the player know when a door is locked would have been helpful as well.
I'm not too bothered by bugs in general since they exist even in full made titles but I'll list some that I came across:
Now that that's over with I don't want you to think that I'm saying all this out of spite. Rather I want to point out flaws that you can perfect and keep in mind while developing new custom stories. I had a great time playing this custom story and look forward to seeing how it developes further. In particular I liked the way you made the player sneak by having them crouch under an invisble wall. That way they couldn't proceed past certain points by simply walking past guards like they weren't there.