Waterless river microbiome, and a taiga microbiome

I was taking a look at the world generation, and I came across this, a waterless river microbiome, and a taiga microbiome. It's not that serious but it's weird and it's still a bug. I hope they fix it, and I noticed something too. Why is minecraft without the mountains? I try to teleport through /locatebiome and can't find any mountain biome written.