The ±1/2 would be tricky too. That's one card with four values. Not sure how you'd do that. Maybe each corner? Or the edges? Might look weird, though. I don't think I've ever used that card in the game, so I couldn't even tell you how it's handled in the game.
EDIT: I cheated it in and checked it out. There is another button to change the value between 1 and 2, just like with the ± button. That's what I figured, but I'd never seen it personally.
I quite like the 2&4 and 3&6 cards, so I'd like to figure out how to utilize them, but it's a tricky issue. If you were to use side deck cards to swap out the values for these, you would need extra 2, 3, 4, and 6 cards to counter the other cards. Now, there are only up to 8 side deck cards being used at any time, so it's conceivable that you could just use extras, but it's highly probable that you would run out eventually. To ensure this would never happen, you'd need extra cards. I did some math. It adds up to four of each - card, plus double amount the + cards that are being used as side deck cards. (They do NOT turn - cards into + cards. I always assumed they did, but I tested it, and they don't.) So, for your layout above, and assuming you don't have to account for the ± cards, that would be 7 of each - card, 28 extra cards total. You would need more than half a deck just for cards that wouldn't even be in play most of the time. Not very efficient.
But there are other options. You could put tokens on the cards to mark which ones have had their values reversed - change, or bits of paper, poker chips, etc. You could also flip the cards sideways.
It's interesting how a simple concept like this is difficult to execute without a computer. On the other hand, I can think of other potential card designs that would be more difficult on the computer because they'd require player input, which would mean altering the GUI. Cards don't have a GUI.
Right, that would take care of all the issues... I have no idea how to go about it, though.
Oh, I like that design. Looking forward to more.