For the 1528 card, I can exactly tell what has been updated, as I contacted support because of that:
When you compare the picture quality of the demo clips her cards 1530 & 1532 (both are Crystal Clear rated). For me 1532 has been greatly improved the Quality to a really good one, it's in my collection. But for 1530 even Quality has been improved, it still having really bad quality, so I denied to buy.
While the 1528 card had their demo clips in the Quality of 1532, but only those. All the others were in Quality of 1530. So I contacted support, and a few days later all the clips were updated to have the good quality of 1532 ;-)
For me by the way, I would really appreciate something like a updated card history list. Something simple like a always updated list with just the date, card name, and short update description would be enough.
So I could check, which cards have been updated recently, and what has been updated.
As for me, Cards which have from my opinion a not good enough quality, I won't buy at all, regardless I like the show or model. I even disable such cards in my collection, if I received them somehow. And they can never be found in my wishlist (of course).
While there are several of those cards, that I refused to buy because of quality. In the meanwhile I noticed by some of them, that their quality have been improved alot in the meanwhile. Which of course is nice and also tells me, that older cards regularly are updated with quality improvements.
But in regular I don't notice those update, except by luck.
A good example are the card of Erica Fontes. All released during the same time period in 2014. Today as marked as Standard Quality. But few cards have been updated with impressive Quality update and are rated today as Cristal Clear. The other cards not (yet?). But there would be updated maybe some more of them in the future. I maybe will never take note of it.