Off-screen notes have always been unrankable, so I don't see how this is anything new or groundbreaking that BN/QAT care about "a few pixels". And they should be caught at some point by modders/BN during modding in the first place, though I dunno how many actually look for these things. + It's annoying to have to change the resolution to 4:3 to check for off-screen notes to the left or right.
It's not a huge deal anyway. Just unqualify, fix the slider, and get it qualified again. Scores get wiped, but that's why it's qualified and not ranked in the first place.