That's looking a bit better

OK, onto the finer details!!!

You have bonus feats listed in the table, but you have also granted continued feat gains from Artificer Abilities, you should really chose one or the other. If you chose to stick with the idea of Artytheurge stacking with Artificer and/or Wizard (is it both?) levels for feats, then don't drop the PrC level by 2 for the calculation, you're already dropping a fair bit to theurge at all!

The percentage is equal to Artytheurge level + Artificer level + intelligence modifier.
This will likely start at about 15-17% and go up from there, was this intentional? Either way, very nice ability dude, I approve and may well have to shamelessly plagiarise at some point (with credit to you of course! )

I do worry that these guys won't be able to fully use their own infusions, since they can't wear any form of armour or shield without spell failure issues, perhaps consider giving them Armoured Mage (light)...? These guys will never get past level 7 arcane spells, and only just get access to level 6 infusions (i.e. 1 of them) by level 20 as it stands, so you can afford to give them a little hand. Especially since anyone who's actually played into this PrC has had to get to wizard 5/artificer 5 within a game, not easy to survive without feeling kinda pathetic!

Perhaps consider giving them an ability allowing them to supress the effects of magic items at the expense of infusion slots, and a second one allowing them to deliver touch range infusions at a distance at the expense of arcane spell slots.