An advantage of an all in one app: it's easier to have consistency.

Please see:
http://i18n.tikiwiki.org/mass+spelling+correction

I agree with pretty much everything you proposed. I'm sure we're not the only Wiki with this issue, and with the goal of Tiki being pervasive in Wiki-land, perhaps these language changes within the wiki data could be made into some sort of normalization feature or mod? Every project has to take stock every once in a while and parlance changes. Weblogs in the early days are now blogs. Making a tool where you can feed it a mass search/replace list I think is valuable, for various languages, aside from leaving it to folks to hack their databases.

In principle though, I think its a great idea to clean up the english language stuff!

This is a pet peeve of mine. And it affects acceptance of the tool. There's an old saying: One "Oh sh$#" offsets thirty "Attaboys." People are pretty fast to reject based on minor annoyances. If the grammar isn't correct, why should they trust their information to the system? We also need to decide on capitalization, such as: Table of Contents vs. Table of contents. Count me in for help on modifying files. Let's divide and conquer. See my page for contact information.