It was an old comments that was later erased that makes us think... why wasn't it updated on the Steemit page? Which other things aren't being updated in data matter?

I think the steemit page is consistent. The account made a (absolutely meaningless?!) comment, which increased its total post count to 1. Deleting a comment does not decrease the total post count. The fact that steemit shows "1 post" but the "Comments" tab is empty is expect IMO, and this behavior can be seen on various other account profiles.