Jappa said the overworld gold ore texture was made different from nether gold ore, because nether gold ore is mechanically different – overworld gold ore drops itself and must be smelted into ingots whereas nether gold ore drops nuggets.
The color of the stone ores is a much better match to tuff than the deepslate ores – just a thought. Even if this is unintentional, I think it should stay.
The nylium side texture ought to be a transparency on top of whatever netherrack texture the user is using. I understand why new textures aren't adapted to fit with Programmer Art, but this simple fix would allow Programmer Art to not be broken with nylium.
Might be "works as intended." The stone ore color is a much better fit for tuff than the deepslate ore color.