That is a cool design. I like the 45 degree corners with shelves for plants. Never seen that before, but one I will see in my next pond I think.
Your soil...looks like no fun. The concrete blocks look to be made of the same material.
If I saw correctly in the pictures...here in the US rebar is required to be completely encased in concrete. Pounding it into the ground isn't allowed. The steel rusts in the ground and follows up into the concrete. Rusting expands and breaks the concrete.
Going back a few weeks...I bought some used bulletproof glass a couple years ago, or bullet-resistant glass (I think the correct term is relative to which side of the glass you are standing when the bullet is fired). Because it's used I don't know exactly what it is, but it is laminated and the outer layers are some kind of plastic. It has scratches and is far from being very clear. I can see (no pun) why people prefer glass. I will probably use it as a window in a pond just because I already have it and it was basically free. Adding windows to ponds seems way cool to me. I've spent hours just watching videos of people's pond windows on YouTube. I get the feeling a deeper pond adds to window viewing, that feeling of space. At least that's how it seemed watching videos.