I should probably elaborate on why Wally has/should have immeasurable speed for running through time:
There are 4 main feats/statements: Wally outran Black Flash, a manifestation of death to the end of the universe where even death ceases to exist on a conceptual level.
Every time a speedster enters the time stream, they break the time barrier and bounce off of the edge of the speed force, into the time stream and in Wally’s case he can move along it however he wants without external help.
Wally and Barry chased Orion’s bullet through time, while being chased by Black Racer, a manifestation of death (of the New Gods, higher dimensional beings, including Black Racer himself, this is probably an avatar that’s chasing them tho), and into Darkseid’s singularity which was collapsing infinite universes.
Barry has apparently stated he can run faster than time, I have not yet seen this scan tho so I can’t elaborate.
I think at least one of these feats could be proof for immeasurable.
Note: Black Flash’s and Black Racer’s speed in the universe is very likely finite so I don’t know if them being an aspect of death changes much.
Wally stating they are approaching light speed in the time-traveling bullet chase in Final Crisis isn’t an anti-feat since light speed is described as a speedster’s terminal velocity, as in if they go above it, they could enter the Speed Force. However The Speed Force Wall is known to denizens of the orrery as the speed of light (which I’m pretty sure implies it’s a speed limit for higher dimensional beings who have immeasurable speed) and Jay Garrick also states even death can’t go faster than the speed of light which could possibly be referencing the higher-dimensional true form of Black Racer as well (after all, Black Racer kills higher-dimensional beings all the time IIRC). So Barry and Wally outpacing light speed in this particular issue is quite the feat (since going MFTL+ in DC usually ignores light speed).
Breaking the time barrier and almost accessing the Speed Force could be a massively beter feat than portrayed here since the Speed Force is very likely 1-A during most of DC’s cosmology (DC’s cosmological size probably varies between the years but the SF should still be higher-dimensional during all of it’s cosmology). At the same time this could lead to some contradictions with Wally’s feat of accessing the 4th dimension and what not so consider this a work in progress.
Sources are in this blog under time travel and speed categories:
http://ulltraguy.blogspot.com/2020/09/character-analysis-wally-west-unaltered.html?m=1