Hallo,
I am happy to let you know that one of the key documentation pages, the one on Filters has now been brought completely up-to-date: http://www.spip.net/en_article2465.html
The only bit I really was unsure about is the |div filter: "corresponds to non-Euclidean division." to translate the French "correspond à la division non-euclidienne ("après la virgule")." Does anyone understand precisely what this means!? Maybe there is an easier way of saying it in English.
Umm... there is a lot more to do. Any keen helpers will be gladly welcomed 
Paolo