On "Irrelevant Speed," here is my quickest run-down of what that actually means:
Speed is defined as the rate at which a character can move.
Movement is the changing of positions.
Positions are points in space, which are defined by coordinates.
Coordinates are a product of dimensionality - Points along axes. This can be extrapolated to every degree of spatial existence. Which is why everything in the current system can currently fit into "Immeasurable." All movements are still defined by changing in positions over a period of time, even if said "time" is unquantifiable by the standard speed formula. This is because nothing is ever actually treated as being outside of these concepts entirely.
However, in Ultima's system, 1-A characters are superior in 'quality' to spatial existence. So all of the things I've mentioned above can no longer apply to them.
Thus, their "Speed" is Inapplicable, as they have transcended the concepts that speed as a concept relies on (space, time, etc).
In this way, no current rating of speed can currently define their existence or "movements" they make on the layers they exist on. "Immeasurable" is still defined by moving beyond linear time, and can be quantified within the universal concepts of space and time. This can't apply to 1-A beings in the Ultima system.
Hence, why I believe some form of "irrelevant" will see its place if the new system comes into fruition.
But, some people might be mistaken. This "speed" isn't a form of quickness, rather, it's mostly just a qualitive superiority to speed itself, rendering speed irrelevant when discussing the characters who qualify. It can't really be compared in the same way that something like immeasurable speed can be compared to infinite speed, since it's fundamentally not the same thing.
It's a lack of speed via transcending what speed is.