I mean sure it could pick a hand that is bad but you could've just as easily just got that hand anyway and there's nothing you can do about it either way, though with the algorithm its possible you are less likely you end up with such a hand.
That being said it could be better to just have a free first mulligan and there IS some argument of sentiment that the computer handed you a bad hand with its algorithm whereas without it there is the idea there is nothing you could've done, though, again, there's no actual difference between the two actions.

You have literally no way of knowing what was in your other hand so... There's no real use in worrying about it.

But... What about when both hands have exactly the same amount of Land? How does it Choose then? My guess is it either always gives the first or the second. Anything Beyond that is conspiracy-theory Territory.

it chooses the first

it gives both hands a weighting based on the number of lands in them and then randomly picks between the two. The weighting is so poor for 0 and 7 card hands that it will almost never pick them, but it has a chance to.

I'm assuming the weighting would be 50% : 50% for two hands with the same number of lands.

At least that's what i understand from how they've described their system where it will, in their words, "lean" towards giving you the "better" hand but not always do so.