Warp/Omen/Adventure issues
My issue is that there is no uniform position for where your card is going to be to cast it normally, and not with its warp/adventure/omen effect instead. Omen is on the right for casting the permanent, and Warp is on the left. I clicked the left side via muscle memory on an omen card and it might have cost me the game but my opponent surrendered shortly after anyways. So where I was intending to bounce everything on his board with Marang River Regent with Starfield Vocalist on the field, I instead drew three and had to discard.
I think consistency in design is important, not only for growth but retention. If you're not consulting a greater design document for implementation of these types of features, I really think it could benefit the teams ability to continue bringing the best digital card game experience they can.