My guess is it's unlikely those would get through - they're strong, but small. But although I have some sort of weasel here (one was walking down my driveway) they've never tested my run fencing far as I can tell. Weasels are less diggers and more opportunists as far as trying to infiltrate underground, they follow burrowing rodents in through the holes they dig. So the goal is to prevent rats and such from digging in in the first place.
Vent coverings I'd be a little less worried about, especially if they're up high, mostly because the pest/predator would have to climb up to the opening, hang on, and chew/tear at the same time - just a little less likely to happen all at once like that.