Research & Development
The visual interest shows well interesting buildings and elements of swamps. Style guide shows several different styles.
Creative Art
The color and stylized approach work well in the image. Material definitions could maybe be pushed a bit further. The turntable looks great with fireflies in engine.
Technical Art
The scene is mostly on gameart level polycount wise. There are a few things I'd like to mention, though; Seeing roof tiles in different scales on different roofs also feels a bit odd, along with the house feeling a bit like it's been built with rock, the round tree meshes are a bit on the high end on polycount in contrast to the wooden pier the house is founded on, which is a bigger mesh chunk. Lilypads could be maybe almost flat planes with applied alpha texture.
As you mentioned about the UVs, you can get pretty great results with automated UV packing in many of the modeling programs. It's mostly about knowing what texel density you'd like to hit, and working from there it becomes more of a problem solving type of thing!
Using tileable texture means having a texture, where if you place the same texture right next to it, it would be a seamless transition between images. Using such texture with a bigger surface calls for scaling the UVs of the mesh in your modeling package.
Use of engine's linear gradient is something I probably wouldn't have thought about, which is super nice, and actually produces a cool effect. For your next scene, you could try looking for similar gradient feature in Painter to save a bit of shader instructions by baking it into the texture. :)
Documentation
Documentation showcases well different parts of production. The text is easy to read, and filled with pretty pictures.
Final Presentation
The presentation showcases different aspects of the scene well. The images look nice and crisp. Water, lillies and fireflies are a nice addition in the scene.