“The doors of Twilight, Princess of Friendship. Say “Friend” and enter.”

“abandon all hope all ye who enter here.”

@Background Pony #2C1E  
Check my upload history. I used the haiku to create a (very rough) translation aid, which can currently (very roughly and with great margins of error) detect the letters A, B, E, F, H, I, L, N, O, S, C, U, V (the most recognizable letter, as it’s a loop above the middle), W and the sound “Ou”
 
Other than that, guesswork and trying to interpret symbolism.

@ThePonyTheorist  
Still say “Derpi” means “muffin” and “Dinki” means “croissant”…

@ThePonyTheorist  
How’d you figure that out?

@Wiimeiser  
Lemme try this out…
 
Remembering that Equestrian language seems somewhat heiroglyphic:  
That first segment looks like “Veh”, “Ves” or “Vew” according to my self-made translation key. Given that Ponehenge said “Poni rules”, i’d imagine that perfect spelling by earth standards isn’t a thing on Equus, and this means ‘the’
 
The rest seems more complicated than the first, translatable line. I’d guess that the two horizontal lines mean “school”, and the / means “of”
 
The H looks like two linked two linked loops. Either this translates to “Vouv”, or “vev” according to my (maybe glitchy or senseless) key, or, I would assume, it represents two “friends”. This heiroglyphic interpretation is supported by the swirl; a symbol which appears with magic, and is highly associated with magic. Since friendship is magic, we can therefore maybe translate this to:
 
“The school of friendship magic”, which could be simplified to “The school of friendship”

@Wiimeiser  
Equestrian definitely seems to be a written language in and of itself. There are some features you can recognize (I can tell upside down equestrian from right-side up equestrian).
 
Of course, if the show staff actually made the language make sense is another question in and of itself.

el = Ho
 
probably not intentional…