The only issue is the fastest run to the finish time has to be without any secret shortcuts, tricks (like getting a guard to open a locked door when that's not really supposed to happen), or other forms of "dumb luck". It has to be playing the way the level was presumably intended to be played - just as quickly as possible. I don't think the following times are possible without playing some sort of twist, usually I'd only envision them if you got a guard to open locked doors when that wasn't intended:
E2L8 0:20 (though that level doesn't matter anyways)
E4L8 0:55 (this is possible with the secret shortcut and no other trickery, but secret shortcuts are disallowed as well)
And there may be others; those are just cases where my confidence level is at least 95% or so.
Is there a way to get best times that were done without any:
1. Secret shortcuts; and
2. Cases of enemies opening locked doors (except E4L7)?
Those would be the times to compare to.
Also how did Autobot manage E2L8 at all?...100% secrets and treasure in that level is absolutely impossible no matter what you do, even if you go for the "best you can" in the Aardwolf Maze. I do notice that 2048 (remove the colon) is 2^11 and bots/programs usually run with powers of 2 in mind; is that 20:48 simply saying Autobot reached its maximum time limited and then stopped running?
And yeah I can see what it would do on E3L7...find all the dead ends in the maze when there is absolutely nothing there, thus padding the time.
Cool experiment nonetheless.
p.s. Regarding Episode 6, I'd think E6L8, even with secret shortcuts, would take over 2:00 to get through. Unless there's some way to get a guard to open the first locked door (that would allow you to skip the entire north half of the level). E6L4 seems possibly marginal for 2:00 as well. (Note that in addition, I am only considering the territory you much go across; extra time to realistically stay alive [though if you're playing on baby that time is drastically cut, but still non-zero] only adds to these minimum estimates of mine.)