It does not contradict how our world is known to work because we have no way of knowing how our world would work with undetectable worlds. We simply cannot claim that the same rules will apply.Yes we can, because your definition involves our world and contradicts how our world is known to work.
I have no idea how you can know what information is like in an undetectable fantasy world. My own guess would have been that this information could not be physical because then we could detect it.Remember, information is physical.
But in any case, I see that we cannot agree, and further arguments seem useless. After all, we are discussing something that we all agree is futile or meaningless.