Hi. The 7 cards limit for the sideboard in BO1 was created to limit the power of "Learn" cards in constructed, during the Strixhaven meta.
Honnestly, it was already pretty overkill at the time. But now, no one use these cards in constructed anymore, and we are still stuck with this 2 part sideboard feature.
It should be reverted, because:
- it's complex for no good reason
- it's always buggy (just typing "sideboard bo1" in this forum shows at least 20 open bugs due to this)
- when using a deck for both format, every time you update the sideboard, it mixes the cards, and you never have the 7 you want for BO1

Either you need to invest a lot of dev time in this feature to make it not-buggy and easier to use; or you should simply remove it (which is imo by far the best solution, less work for you and way better for all the players).

Thanks