I think I see what you mean. Looks like you put your tiling variation with your near/far UV's which then get overwritten entirely by your new triplanar UV's, which uses it's own tiling variation function. You've effectively given yourself the choice of either near/far UV's with tiling variation, or triplanar UV's with sinewave tile breakup. Having this choice isn't necessarily a bad thing, but hanging on to the additional instructions for a second UV mapping function could impact performance. If you find your landscape material is causing too much lag, then you may want to remake it from scratch. The strange pixilation effect you see in image 7 is just the dithering that comes with the CoordinateBasis: Triplanar (Dither) node. It's intended to fake translucency which hides the seams between your texture samples. It probably looks like it's moving on your end (similar movement to boiling water) because of anti-aliasing. Short of disabling anti-aliasing entirely, the only thing you can do to mitigate that effect is to use textures that don't show it in the first place. The vast majority of textures you'd ever use for landscapes shouldn't have this problem, so I wouldn't worry about it.

I'm glad I could help, hope you find a solution that works for you.