That graticule makes absolutely no sense. It looks like a Mercator graticule that's been stretched out drastically east-west, or squashed north-south. There's no reason to do that is it breaks the key thing that Mercator does, which is to preserve angles, particularly compass bearings.

As a rule of thumb, the 'boxes' at the equator should never be wider than they are tall in a cylindrical projection (one where the graticule is a rectangular grid). If they are, it means you are adding pointless distortion to every trait of the map (angles, distance, and areas)

Having your neatline intrude into the map extent (the rounded inner corners) is bad practice. You don't want the neatline to interfere with the map at all.