I'm assuming the use of "cave-at" means the author has inferred an etymology of "caveat" being made up of "cave" and "at", as in: this guarantee has a limit beyond which we cannot keep our promises, if we ever find ourselves AT that point then we're going to CAVE. (As in cave in, meaning give up.) I can't think of any other explanation of the odd punctuation. Really quite charming, I'm sure I've made similar inferences in the past and ended up spelling or pronouncing a word completely wrong until I found out where it really comes from. There's an introverted cosiness to this kind of usage, like someone who has gained a whole load of knowledge and vocabulary from quietly reading books without having someone else around to speak things out loud.