Well, to be honest, I think the way to go in Nobilis is to insist that time and space are not physical objects, but that the prosaic world of course is reinterpreting them in a certain way as a result of the current configuration of the universe. But beyond that -- time already exists in the Chancel, which makes it a matter of Change and not Creation. And even 1 MP is precious, considering how few we get. Keep in mind the example about Rook and her using a Creation of Eternity to toughen herself up: a Creation of Eternity is like a free gift, but a Lesser one runs out at the end of the scene, whereas a Major one will last until disenchantment. A Major Creation is worth about as much as a gift, because of how many MPs you need to spend on it; players are usually loath to casually spend them, and, much like a wizard, if you spend all of your MPs in one scenario, there's nothing stopping your foes from advancing in the very next moment.
But personally, I'd say that a Lesser/Major Anything of Time would affect either one person or one area -- so there hopefully wouldn't be an "I only affect my army and not yours" scenario. And as for the moebius strip of space, I'd say that, since it has no connection to the Chancel, then Realm cannot create it as it attempts to do something outside of the Chancel and therefore is not part of it. I think that a Lesser/Major of the concepts you're talking about probably should be feasible in Realm, but, as always, Realm has significantly more restrictions than Domain does, and so the miracles that you're talking about may be beyond even a Tempest's power. (And keep in mind that even if you penetrate Auctoritas, you can still only affect a Noble indirectly -- you can shoot a bullet at them, or enclose them in a boulder, but Time and Truth of a Noble are likely inherent concepts that do not fall into a domain, and thus can never be affected even if Auctoritas is penetrated.)
Keep in mind, by the way, that an invading (mortal) army should be the equivalent of an insect attempting to storm a fortress, or at least, that's what the game suggests. (I forget which section of the book talks about how Nobles are expected to treat mortals with casual excessiveness.) Mortal threats are more or less easily quashed, and only Nobles or higher have any significance in terms of pure battle. This is even moreso true in one's own Chancel -- I mean, the True King can even grant the Durant gift to literally everything. But mortals can be even more powerful than Nobles in the game of information.
Though of course Time's Regal could come pay us a visit and clear things up. ^.^