Recently I have been exploring the great additions of land provided by Tamriel Rebuilt, but have been slightly irked by the sudden splashes of low res textures I see when looking through a lot of the new content. It's pretty drastic. So I considered looking for a texture replacer but the number of mods people have made for the new regions are minuscule to say the least or at the most, incredibly hard to find. Does any one know of a texture replacer for TR?

The textures used in TR will be the exact same ones your game uses for Vvardenfell.
Except for unique objects created by the TR team, like some of the creatures and armor.

Thanks for responding so quickly. I'm aware of the fact that it is mostly vanilla textures but just as you said there are a handful of newer textures. These are the ones I am asking about. I know it might be a unreasonable of me to want them re-textured but they can have a very noticeable difference in quality with all the stuff around them. Based on what you said though I guess that would answer my question as the task does sound unnecessary and impractical as I remembered just after posting this that all the textures and meshes are in a BSA. My bad.

does this mean, that mods like TR or Mournhold Expanded will overwrite texture mods like richer textures (by Lattice) and AllConnaryTextures? is it save to reinstall those texture packs over these mods again?

Mods will use Bethesda textures by default, but will use any modded textures if you have them installed.... unless they come with their own vanilla-altered textures.
You don't need to reinstall texture packs after, unless the mod also has texture-replacers in it. TR doesn't have any texture-replacers for vanilla textures. (as far as I know)

make sense?

actually it does, yes thanks. I just remember installing quest mods which required me to overwrite a great deal of already existing files, so I assumed they simply replaced the modified textures/meshes with their vanilla (lower quality) ones.

It does happen that some mods, for unknown reason, have few stock textures saved. And upon installing mods if you say yes to replace all, it will replace the new ones with stock ones from the mod.