Some things that might need to be added for DN

I think DN needs to have a function added to put counters on as well as removing counters from a card. It can be within the same UI as going over the card with your mouse, or you could have it at the top with dice, coin, and token buttons and have it similar to the UI like overlaying for Xyz. A function to add with this is when a counter is added, just have a circle or something at one of the top 2 corners of a card with a number inside the circle. You can also have a function that will make the circle disappear from the card when it is removed from the field or all counters are removed, or have duelists manually remove all counters from the card before sending that card wherever it's going. The reason to add this function is so that duelists will not forget which card has how many counters on it.

Swords of Revealing Light and other cards like it could use this function as well and have a counter removed for each end phase of the opponent to help keep track of that or any other cards that require a set amount of turns for an effect to activate.

One more thing DN can have added is when a monster is face up, they should add a box under the Atk and Def for when either one of them changes, (and you could even choose to add counters near these boxes or next to the Atk and Def). That way, no one has to keep trying to remember who has what atk and it can all be seen on the field.