The other alternate mental picture I had was that Modern Equestrian is a dual-type language like Japanese, with Earth Pony phonetic script like the hirigana and the Unicorn glyphs like the kanji.
Most of my fanon Equestrian language hypothesis stems from a calculated guess based on their cultural personality and language usage.
Pegasi would primarily use writing based on sign language that could be manually communicated in flight or as large, easy to read cloud signals, so it'll be great for signs and easy to understand.
Earth Ponies would need a language that's practical and usable from a reading/writing standpoint, something that sounds like its written. Therefore they would be likely to use phonetics to shape their writing, making it easy to learn and flexible for adding new words.
Unicorns would have a more intellectual bent to their writing, for conserving abstract concepts used in their magic, as well as good for mathematical calculations needed for some kinds of spells. It should also be flexible for poetry and wordplay, like the glyphic characters used in Chinese or the hieroglyphs of Egypt.
edited 27th Nov '12 12:23:40 PM by AceOfScarabs