Re: Seeing in tongues?
Well...you can add all the infravision-capable characters to a group (say, for the sake of example, Group 'I'), and then post all the you-can-see-in-the-dark information in that group's threads, which only those characters can see. You'll still be writing two posts for every description...the main group (Group 0, typically) and the infra-group...but as mentioned, you won't have a lot of gobbledygook cluttering up the main group posts that would give the non-seeing characters clues as to how much is actually in that room that they can't see at all, which will happen if you use a language option for the same purpose.
Or, as mentioned, you can make it one post, but include secret lines to the IR-capable characters. You'll have to select them each time, but that's pretty straightforward, and if you copy the code from the first message to your notepad/sketchbook/whatever-online-note-taking-option-you-use, after the first time you can just C&P all of that. Then you only have to post once, the non-seeing characters get nothing to tip your hand about what's actually in the room, and the night-vision/infravision crowd get to see everything you intended, all in one thread so the book-keeping is easier.