From the article and video, looks like the requirements are a thin tube and a block of translucent material to focus light onto the tube. And presumably the tube needs to be the right length, to give it enough sun time to react at a given flow speed.

I would guess that while the leaf shape in particular is not required, the loose space-filling curve is a good shape for the tube to get the most use out of the block. Could it perhaps be slightly more space-efficient with a rectangle and a heater-coil shape? Maybe, but I'd expect not by much, and I would expect other resource constraints (the reactants) to matter before you've filled all available sunny spots and need to maximize medicine-per-square-meter, if only because sunny rooftops are not exactly high-demand space.

I saw the leaves, read the article, then thought the leaf structure was a mere contrivance that wasn't necessary and perhaps made scaling manufacturing actually a bit harder/expensive than simpler geometries (neither chem nor manufacturing are domains I claim to understand, so someone more knowledgeable may have real insights).

The change from silicone to rigid stuff also smacks of way better insect resilience in the field. (n.b. photochemistry to work under 3 bar as to keep plastic from creeping into leaky balloon form.)