Study sets are great and i love this feature very much but i think some additional improvements will make it extremely useful and great.
For example how much I remember the cards, if there is multiple option as in Anki such as easy, good, hard & again rather than know it or not will improve smart learn and add filter cards queue, some cards i forget it at all while others i just forget a little bit of it so the only two option make them equal.

Although if there is an option for backward of cards as I accidentally pass or option for editing card in when learning as sometimes we miss or write wrong things it will be very helpful.

Another thing is text cards, if there is an option for highlighting some texts it will improve the functionality of text cards.
At last, sorry if i couldn’t make myself clear as I’m not a native. I hope u get the point.