Oh that makes sense - apparently bpy.ops has a current context that the transform acts on. Instead could you move the transform call outside of the loop after establishing the first block as the context? That's how I would instinctively do it, to avoid checking i in every iteration when I know it can only be true once. Totally minor critique lol.

I'm not a Python programmer but just intuitively it seems like if i==0 will make the first block fall right after it's created. Shouldn't it be if i==25? Or does it work because the loop has time to generate all the other blocks before the first block has time to hit the second one?