In my opinion, the only artwork that does stand out as problematic is the Priestess. I mean, not only is her outfit extremely sexualized for belonging to a religious order, but it is also ludicrously impractical from any conceivable point of view. WHAT IS GOING ON WITH HER SLEEVES?! Those things must drag on the ground constantly.... They'd be a massive hindrance and probably be covered in filth.
The other mages are completely fine though. The female Beastmaster is somewhat scantily clad, but the artists were clearly going for a tribal theme, and her outfit is still practical and "realistic" looking with that in mind. The Forcemaster is wearing a robe and skirt over light leather armor (it doesn't really look like a corset to me). Since she's kind of like a jedi instead of a traditional warrior, that makes perfect sense. The Druid is sexualized, but there are plenty of real-world nudist "hippie" communities, and the druid is almost certainly referencing that with her "natural" clothing. The female Wizard is not sexualized whatsoever. The female Warlock, while wearing less armor than the male version, does still wear decent amounts of armor and looks ready for a fight. I do kind of wish the Siren was less humanoid (more of a mermaid), but it's not all that big of a deal.
I also don't have a problem with the angel artwork in general (although I do dislike the Guardian Angel being half-armored; pick one or the other!). Both male and female angels are depicting wearing very little armor. A lot of real-life artists also depict angels this way (probably because of the Bible passage about people not being ashamed of their bodies or wearing clothes until after original sin).
While only the Priestess artwork is really problematic for me personally, I do see your point about male and female mages being treated differently overall, even if the difference is sometimes subtle. That's why I really love the Dawnbreaker's Chosen art, and wish it was the (eventual) female Paladin. It would be great to have at least one really heavily-armored female Mage, and I'm also looking forward to seeing how Arcane Wonders eventually tackle the male Druid.