Marisa: a) The feat is still unquantifiable, so just by that means I would not just write it down as large planet level or anything.
b) Not all spellcards are literal. Example given "Eight planets in two orbits, opposing one another.
The planets do align, but there's still a little space between them. Retrograde orbits are rarer than this." From Blazing Star "Planetary Revolution. The planets refered to here are clearly not real planets. Marisa has never demonstrated anything close to this otherwise or even a type of magic with similar properties to this. So I question this.
Not sure about the feat of miko, as I haven't looked through the more recent games (12.3 and further as active). Mind to give a link?
"Dreams are physical": To quote doremy here: "Prepare yourself well, dreaming human of the physical world." So the physical world describes a set of things that is not of the place they currently are at (or that doremy isn't from), which is the dream world. Quote is from reimus scenario. So no the dream world is by no means physical, its stated that it isn't.
"Dreams in the Dream World most of the time imitates the real world"
Quote from doremys profile: "She lives in the world of dreams. The dreams of all living creatures are, in fact, connected at the deepest levels. This is why in dreams, you can visit places you've never seen, meet people you've never seen, and find glitches you've never seen either."
The dream world is quite literally the place where you (as in usually your non physical body) is at when you dream. As such to a degree its true that it would most of the time seem similar to the real world, but that doesn't eman that its structure and properties is the same. Imitation only means good enough to seem like real, but not real. In this case the stars just like the random red lines and birds don't have to be real, they can very well just exist so that the one that dreams feels believes they are real. In short the fact that they are dreams is enough reason to doubt anything there works much like it usually should.
In my opinion we shouldn't go for MSS or MHS here even if possibly, its just too much of a stat difference for way to many characters. At least that is my view of it.
BTW. you asked about the femtosecond thing. Its fromhere.
To quote: "Femto, to put it simply, the instantanous. A period of time so short that normal living beings can't even imagine it. Tiem is made up of countess instants so short you can't percieve them" So Femto = instant it seems?