Overall your work is quite well done, though there are a few points I want to draw your attention to. So, let's get started.

Your form intersections are coming along nicely - the forms themselves are drawn well, they feel cohesive within the same space, and you're demonstrating a solid grasp of how they all relate to one another in the space they share. The only issue here comes down to how you're applying your line weight. As we can see here it gets somewhat scratchy, suggesting that you're chicken-scratching the addition of line weight, likely out of fear of losing your accuracy if you actually make a confident, consistent stroke.

Yeah, there's a chance you'll miss your mark, but you need to be willing to accept that potentiality. Line weight must be applied using confident strokes executed with the ghosting method, the same way you'd have executed the original mark. Do not change your approach out of fear, and do not trace back over the existing lines. Tracing causes us to focus on how the line sits on the flat page, rather than how it represents an edge moving through 3D space. Confident executions also make the stroke taper on both ends, making it blend more seamlessly into the existing linework as shown here.

Moving onto your constructions, aside from the line weight issue still being present in some places (again, remember that line weight is focused on clarifying the overlaps between specific forms, and shouldn't be applied to the entirety of a line or silhouette), you have largely done a solid job at applying the different strategies for constructing hard surface and geometric constructions. Even though this one spills outside of its initial enclosure, I'm very pleased with how you laid out all the subdivisions and pinned it down with considerable precision and planning. As a result, it felt extremely solid and cohesive.

For this shelving unit, I'm also very happy with how you leveraged cast shadows and avoided getting caught up in any form shading to more clearly and effectively convey the relationship between the different forms - the sides of the shelves against the horizontal boards, and even the entire structure with the ground upon it was standing.

Even your kunai - which was a pretty complicated kind of structure to approach, was built out very well, laying out all of the necessary subdivisions to achieve a solid, believable end result.

The only area where I believe you fell short was when you placed ellipses - like the dots on the die, and the ports on the gamecube - on your constructions. All of them were generally laid out more approximately - you eyeballed their position, and it would have been far better to first construct a specific plane in which they'd sit, snugly against all of its edges. To achieve this plane, we'd of course need to subdivide further, but the result would match the precision with which everything else was built.

Everything else really is coming along great though, and it's interesting to see that the one weakness is also a direct contradiction of what was otherwise your greatest strength - so hold to that instinct to subdivide as much as is necessary, and don't allow yourself to eyeball or approximate anything.

I'll go ahead and mark this lesson as complete. To answer your question there, you are free to work on the treasure chests. I generally expect students to finish up Lesson 6 prior to tackling them (for obvious reasons). In most cases, it's left until after Lesson 7, but there's no firm rule on that, nor any good reason other than "treasure" following the "big boss". Of course, despite that, I'm still going to mention below that your next "official" step is to move onto the 25 wheel challenge.