anyone know if I definitely have to swap them out or just advisable for perfection
Again, those look fine. Basically two oddly shaped board now. If you're happy with the split aesthetically, then leave it.
When you say 'punch the nails in far enough' do you mean anything other than hammering so they're flush with the board?
You'll want them a little below the board as you'll be taking some wood off. Even with punching them all down, some of them didn't go deep enough and I ended up sanding a lot of nail heads. A punch and a 4lb lump hammer makes short work of it. Just be methodical and go along each board and you'll be done before you know it. The bigger hammer just means it's going to be one whack for most of them instead of relentlessly tapping with a regular claw hammer (unless you take a big swing).
Again, those look fine. Basically two oddly shaped board now. If you're happy with the split aesthetically, then leave it.
You'll want them a little below the board as you'll be taking some wood off. Even with punching them all down, some of them didn't go deep enough and I ended up sanding a lot of nail heads. A punch and a 4lb lump hammer makes short work of it. Just be methodical and go along each board and you'll be done before you know it. The bigger hammer just means it's going to be one whack for most of them instead of relentlessly tapping with a regular claw hammer (unless you take a big swing).