Laura, I’m enjoying the scene. I also think that you’ve got an interesting balance between the rocks at the bottom and the mountains at the top. The underwater rocks and the light/dark pattern keep the big expanse of lake interesting and attractive. The blueness adds a sense of melancholy. When I look at the raw file, I don’t see any need to “level the horizon”. This is clearly a long narrow lake, so the lake edges in the distance MUST be at a steep angle to your point of view. The rules for translating a 3D view in 2D require that those edges NOT be level. The amount of sky in the raw file looks reasonable to me. That distant peak near the right edge needs more separation from the frame in your adjusted view. Since this is a glacial melt lake, I expect the water to have a strong blue tint, but less so in the distant mountains. Adjusting blue in distant views is something that our brain does automatically, which means it’s artist’s choice to adjust it or not. Should you want to make an adjustment, you can easily do that in photoshop by adding a saturation layer, dialing down the blue saturation (and maybe the blue luminosity), add a black mask to the entire layer and finally paint white into the mask to control where the reduced blue is applied. You can adjust how strongly the mask applies by using a 25% opacity brush and going back over the same areas in the mask up to pure white.
BTW, since you already have photoshop, it’s a fine way to learn about stacking. However, if you look at a stacked image in PS, you’ll find soft spots, because of the way PS creates stacks. I showed that in my stacking webinar a couple of years ago.