Many countries globally have the ability to manipulate their currencies vis-à-vis their central bank. The TPP does not necessarily have enforceable mechanisms by which you can prevent that.
You've read stories about China, for example, devaluing its currency, and Thailand with the baht. All sorts of examples globally have happened over the last 10, 20, or 30 years involving currency manipulation. I don't think countries put out a news release to say, “By the way, we're doing this”, but it happens globally, and it's something we have to take into account when doing international trade deals; there is no question about it.