I think this is a really common misconception around Barcelona's superblocks.

When people hear "Barcelona superblock", I think they're thinking of the individual city blocks which to be fair, are already huge and modular. (this is at least the confusion I originally had)

The idea with superblocks, is to take a cluster of city blocks and not allow through traffic in that block, instead guiding that traffic to flow around the perimeter of that cluster. Nothing here requires the city blocks to be built or look the way Barcelona's city blocks are built and look. All that's required is changes to the roads, and to try and encourage each cluster of blocks to have a mostly self sufficient set of amenities like a grocery store, cafe, etc.

In unicode art, if □ is a city Block surrounded by roads (-- and |) being used by traffic,

    |_|
   ‾|□|‾
   ‾|‾|‾
    

then a 3x3 area of these blocks would look like

   _|_|_|_|_
    |□|□|□|
   ‾|□̅|□̅|□̅|‾
   ‾|□̅|□̅|□̅|‾
   ‾|‾|‾|‾|‾

However, a superblock would look like this:

   _|_|_|_|_
    |□ □ □|
   ‾|□ □ □|‾
   ‾|□ □ □|‾
   ‾|‾|‾|‾|‾
     
     

where the inside area is not easily accessible to car traffic. The structure of the block □ itself, doesn't actually matter.