Why would one need to "develop" a gut biome to eat cheese/dairy? Have you ever heard of breast-feeding? Yes, you may be surprised to hear that even Asians can breast feed.
What you seem to be thinking about is lactose intolerance, which is not due to a gut biome issue but due to genetic or environmental factor causing a deficiency of lactase, a protein, after infancy. Lactase persistence is not common in many ethnic groups.
There is evidence that a biome habituated to certain strains of lactobacillus can allow those that would otherwise be intolerant to become tolerant, but that has nothing to do with the cause of lactose intolerance.
> Whereas one of my exes was Asian and would get IBS whenever she ate cheese.
IBS is a functional digestive pain syndrome. It has nothing to do with lactose intolerance. For someone epeening about their medical knowledge, you seem to know very little to back it up.