2+ million year old data?

That's a very valid point. 

Sometimes you just have to pretend things don't need an explanation, like the Geth Telescope.  Other times its best to just pretend it didn't happen at all, like Project Lazarus, the ME3 endings, and Superman IV.

I mean, let's not act as if this is new to the series. The titular Mass Effect is explained (and even then there are holes when it comes to stuff like Biotics) but beyond that? Even in ME1, which was the closest to wanting to stick to hard science, you still had stuff like the Thorian which wasn't explained by much more than ''spores did it'' or the Prothean beacon that somehow plants visions and language into the mind of a being that's utterly alien to it, and makes them float for dramatic effect.

In fact, it's hardly new to sci-fi as a whole. Even the likes of Star Trek and Babylon 5 have lots of weird stuff happen and you just have to take the series's word for it that it works that way just because. 

As far as sci-fi explanations go, ''these technically adept AIs used the resident FTL portal network to create a superpowered telescope'' isn't exactly a giant stretch to me. And as you said, the series has had far, far worse in terms of scientific absurdities. 

I'm certain some form of Trekkie technobabble could be conjured up to explain it, like the relay's built-in sensor used to pair with other relays were reconfigured to transmit a signal through its mass free corridor (which would be virtually endless without a partner relay at the other end) and the signal simply bounces back when that signal interacts with any bodies in its path giving them a closer to real time view of the cluster. Then the geth all do the robot because of how insanely scientastic they are. 

Then why weren't they using them to spy on organics? Why haven't they used it to spy on their home planet 598 years into the future? What's good for the goose, is good for the gander.

I'm honestly unclear about what plot problem the telescope was supposed to solve. Inhabitable planets are unlikely to all go uninhabitable in a couple of million years on their own, and since there are multiple worlds one going bad wouldn't sink the project. And if you're worried about intelligent life arriving and taking over, a 600-year window won't really help

Lo ... LOL ...LOLLLL... LMAOOOOOOO  ...  Sorry I can't stop laughing, Mr Walters and Bioware using logic ... LOL  oh crap here I go again.

OP doesn't keep to the BioWare Mantra to look everywhere, ask everything and read all codex entries.

MET's technology enabled FTL travel at a rate of ~ 12 LY / day.  At that rate, it would take ~ 600 years to travel the 2.5M LY to Andromeda.

If Protheans can build a Relay in secrecy, nothing says the Geth can't jury rig them to work from the opposite side. 

Of course, it's jury rigged, so they couldn't use the subsequent construct to travel (that would have saved the Initiative quite a few headaches) as it wouldn't be powerful enough to move ships. But it's good enough to have a rough estimate of how Andromeda looks within a few hundred years, which is almost real time when such distances are considered. 

Given that the Omega 4 Relay could also (dangerously) send something through without having a sister Replay on the other side, there is precedent for that kind of thing. 

Agreed.  In a fictional sci-fi universe I'm pretty willing to extended a lot of rope in the suspension of disbelief department but taking, what did Jacob call it, a pile of meat and tubes, and turning it back into a person?  Not only that but a person with all their memories, skills, emotions, and personality quirks still intact with zero side effects or even a shred of emotional stress or instability?  Yeah they lost me there.