OP is sure right about that one. In Revendreth your sins are being dragged out into the open, you get punished for it and are forced to confront them. These sins include murdering thousands in pursuit of knowledge, treating others as expendable, documenting suffering without attempting to stop it, producing perfect toxins that desolate entire species (These are the sins Herald Temel proclaims to have been Inquisitor Stelia's sins). Especially 'desolating entire species' doesn't seem like 'doing nothing wrong'. Revendreth is where you go when you did wrong and horrbile things in life and you do get punished for it. And if you are unrepentant even after eons of punishment and make no progress with changing, you get sent to the Maw.
I really think that there is no way a mortal being can actually go to the Maw without going to Revendreth first, because no mortal being is born inherently and exclusively evil. And no mortal by themselves can do things that disrupt the cosmic balance. You always need the help from a higher power for that. Even if you 'desolate entire species' you don't actually upset the cosmic balance enough to seriously endanger it. Which is the only scenario I can see how a soul might get sent to the Maw first, because committing atrocities sure isn't the reason.