>>/5787/
Now, something else: I consider the flow of the earlier chapters to be weaker than the later ones. Particularly chapter 2. First he is boarding the train, than he notices some odd griffin like things. Than he is in Canterlot saying:
> I need a little bit of time before resuming my routine and...
> WHAAAAAAT?! What is this?! What am I looking at? How is it possible that the door locked? Why does it have a note saying that they are looking for a replacement? They offered this house to me in exchange of doing my job properly and now after all these years, they are turning me out of this place. 
This line in particular felt awkward to me. It feels too... expository. Though that is perhaps not the right word. I think that he just went right into saying what and then mentioning what he was reacting into in a way that feels awkward and inorganic.
You can just add something like this:
> I noticed a lock on my door. Stranger still there was a note, painted in bold black lettering. 
> As I read it my blood went to a boil.
> WHAAAAAAT?! What is this?! What am I looking at? How is it possible that the door locked? Why does it have a note saying that they are looking for a replacement? >They offered this house to me in exchange of doing my job properly and now after all these years, they are turning me out of this place.
Or even a more simple fix:
> I noticed the house was locked. 
> Why does it have a note saying that they are looking for a replacement? 
> They offered this house to me in exchange of doing my job properly and now after all these years, they are turning me out of this place.
Even just changing one of these things to an observation rather than saying what first makes it better. 
 >>/5423/
In chapter 5 I think you do it better too:
> Suddenly, I stepped over a different surface. Under my hooves, I noticed something metallic under my hooves and the feeling was completely different to what I was used to sense for a long time. My eyes opened up after feeling that difference and to my surprise, I found a ray of hope in this hollow part of Equestria:
“IT´S A RAILWAY! I´VE FOUND A RAILWAY! Someone must be living in the south, they must be there!” I exclaimed with absolute happiness.
I think this is fine. Your intorduction of the railway is much more organic and focused. He was in one location and was introducing facts weirdly like say:
> "Oh look, it's the southern railway! That must mean that I have found the legendary magic rail road from which I have know since foalhood when my Mom told me. Frankstienburgstan the city of my birth where the rails supposedly led too!" In one scream. So don't discard this entirely.