It's actually been over 6 months since they gave any update. We're on month 4 since summer though.
I agree with you. I don't think this was a scam, like you said they have put in real work that wasn't something they could just pull out of nowhere. Work they did after they got the money, which doesn't make sense since Kickstarter doesn't actually require an end product to be released and won't offer refunds unless the creator does it. Since it's a crowdfunding platform, people don't actually buy a product, rather than fund a project in hopes of getting an end product in return. Most likely, the artist or both of them got burned out, and progress on the remaining CGs came to a standstill. What's unfortunate is that if my guess is right, they really should've been transparent about their progress. Now they've really burned a lot of bridges, and a lot of their supporters are pissed.
I'm still holding out hope that we'll get a surprise update with the release date, when the game is 99.99% done. Doubt they will give another update before all the art is done.