The section on the Braavosi language is really interesting and deserves to have a wider audience. It really shows how commited this community is. Maybe reference could be made to it in books in chests, or signs on inns or ships? I think it would be really cool to have a few easter eggs relating to it.
Also, on the subject of language, does it really make sense to have all of Westeros speaking the Common Tongue? Maybe a Song of Ice and Fire is actually translating what is a very wide array of different dialects which may not even be fully mutually intelligible, like Arabic? There is a vast amount of potential for this: we could be mapping out movements of people, relations to older languages, development of architectural styles based on different groups of people, the gradual mixing of Andal and First Men languages and traditions... This has so much potential.