This is mostly just a nitpick, but in Part 3 at ~74%, there's a bit about "soil slime". I feel like this should instead be "slime soil", to fit with the naming conventions of all the other "slime [noun]" things that have shown up so far like slime umbrella, and slime lamp.
In Part 3, at ~78%
There is a description of the area inside the castle walls:
Inside the castle, there were livestock pens, a brewery, a flower garden for raising bees, a chapel, a weapons storage room, and many other facilities I couldn't keep track of.
I think it would be better to use some form of "on the castle grounds" instead of "inside the castle", as the latter implies all of that stuff is in the actual castle building, rather than on the premises within the castle walls.
On the castle grounds there were...
On the grounds of the castle there were...
The castle grounds contained...
The grounds within the castle walls contained...
Within the castle walls there were...
Inside the castle walls there were...
Within the walls of the castle there were...
etc.
In Part 4 at ~38%
The part of a saddle that is described here as a "protruding part shaped like a doorknob", and referred to as the "saddle grip", is called the "horn".
Though, I suppose if you told someone who's never ridden a horse to "grab the horn", they'd have to think about it for a moment. So I guess it works either way.