It goes on to mention the two loopholes of using a mundane intermediary and being paid in arcane goods (vis or other magic items); do these loopholes inherently get around the limit of distributing permanent magic items to the mundanes?
Depends on your local tribunal, but yes and no at the same time.
It's one of those where you don't want to piss off a local quaistor, especially as a verditius, for just that reason. It skirts the edges of the code, hence peripheral code...
So I'd say it's technically legal for you to trade a magic item to a mundane lord in exchange for vis he's somehow harvested or acquired. It's also canonically absolutely legal to swap like for like on magic items, indeed it's kind of expected of magi that they give a better item with a limited duration to recover a permanently enchanted item from mundanes. No violation of the code there.
But if you've pissed off a quaisitor, there's good odds they'll lean on you.
Made the item to a specification given by said Lord? Are you a court wizard now?
Traded an item for Vis? That's getting paid by a mundane. That makes you a court wizard, doesn't it?
As to the mundane intermediary, that's the whole point of a Venditor to a verditius.
As BlackLiger said, it really depends on your Tribunal, specific location within the Tribunal, covenant prominence, and your relationships with other members of the Order.
In one Tribunal, you could use a mundane intermediary to trade a charged item that will help a noble knight's land flourish a little bit for his powerful ancestral (and, perhaps more importantly, permanently enchanted) sword and you'd still get dirty looks and whispers behind your back that you're the foot-kissing servant of a mundane lord, if not outright called out and punished at Tribunal if you already had a bad rep. In another Tribunal, you could regularly use intermediaries to trade your lesser enchanted (or even greater enchanted) devices for large amounts of silver to a bunch of different rich landowners and, as long as you didn't appear to be beholden to any particular one of them, nobody else would care because they're all doing it too.
To put it another way, it's one of those rules that is only enforced to the disadvantage of the politically-unpopular or in case of gross abuses. Verditii selling magic items to mundanes through venditors is a perfectly normal and acceptable business, but if a rival wants you out of the way, they'll find or make up some way in which you're violating the Code.