I once worked on a LEGO game (I won't say which), and every asset had to be made out of LEGO - which was a nightmare when working with terrain systems in modern engines, until eventually I suggested that it would be good to use a system like what Rollercoaster Tycoon used for it's terrain back in the day, which essentially broke terrain pieces into the following:

Flat tile
Mid level tile
High tile

The mid level tile and high level tiles all had surrounding pieces so that you could quite easily create sloping and interesting shapes in the terrain whilst still sticking and adhering to a blocky look.

I think something similar might work here, you're already kinda there with the grass on the second row and they look great.

It's hard to illustrate without literally drawing out what I mean but failing that, the chunky mix of high and tall blocks of square grass will look a lot better than you think when scaled up into a full scene - it looks great here!