I think you’re on the right track! I do think these two are off when it comes to their shadow. If the light source is coming from one end, shouldn’t the shadows follow? I do think you’re doing good tho 👍

So I haven't trained prespective that much so take this with a grain of salt but there's a whole website dedicated to that exactly named Drawabox (literally that's the name). Don't know if you've heard of it but I believe you'll find a way more active and specialized community. I checked it a couple of times and they even have a Discord server and stuff!