Wow! Excellent, immersive, original. Very creative, obviously tons of sweat poured into this. Outstanding.

it works with IFA3_AIO with no issues. Every asset seems to be present

Ermm What the Feed...

I was entertained.

That actually might be a good guess. Explains why I never saw it, since I waited for the autosave to finish because I knew in advance that it was coming up.

It's not really a muscle mem but rather having a backpack and option to open it through scroll menu that shows up and dissapears in different situations when mounted. Rest is valid, I understand your choose.

I'll do another playthrough of your scenario later and see what could go wrong with that conversation layer. If it was done as UI (disableSerialization) it has to be reinitialized through mission event handler or it will not show up. If its not done that way then I'll think of anything else. At one point you can choose to help one guy's father or not and dialogue is played when you start the holdaction, but game saves at the same point and requires you to do holdaction again, maybe because it triggered twice something didn't want to initialize later.

Libertad horses are alright, they have one drawback (last time I checked): they cannot jump. Also, dbo_horses have the racehorse.
Figured leave UAV wouldn't be such muscle memory for most people.

As for the missing dialog after loading a save I really have no idea. No other effect uses the same layer as far as I know, which is usually the issue. Have not encountered this problem, will try to find the reason though.

The natives will attack you, as you are trespassing their land. You are supposed to retreat back to the village (as the optional task says) and talk to other locals, if you wanna do the other quest route.

Out of order triggers should be rare, but it seems a couple slipped by at the very beginning of the mission.

Conversation text for every convo went gone when I loaded from a save (I think so at least), didn't want to restart whole mission so I continued just relying on task descriptions lol.
Some task triggers can be triggered out of order, I activated all poster quests at once and while travelling to one of them, I approached a shed north of main city and activated convo with a farmer and a priest, and talked to sheriff later, having the game think I didn't talk to farmer yet. Fortunately quest removed all subtasks when completed so this isn't gamebreaking.
Another thing was that I couldn't talk to the natives, they started shooting at me on sight, had to kill them. Later I thought that they may have said something but I didn't see the subtitles.
Horses are very annoying, a dozen times I clicked on "leave the UAV" instead of get off and had to reload. Wonder why didn't you use Libertad horses, they seem to be a bit more user-friendly.