The word is from the word "to inform", conjugated to "informer", "information", etc. However I'm unsure how you'd conjugate the word used in 29:27, and 57:26 to, in English. Our Lord, when He uses it in this situation, it's a reference to the information about that which pleases, and displeases him, right? So He uses the word "the", because He doesn't just mean "information/ informer", or "an information/ informer". I'm of the perspective, I'm of the perspective it's because He's established what He means with "the information" throughout, and as such He doesn't state "about that which I'm pleased, and displeased with" whenever He mentions it, and instead refers to it (about that whi...) with the use of a "the"...