I agree with mrmandias on robot. It's perfectly fine to describe it in a way OTL readers will get instantly. Of course, one easy way to split the baby is to have the characters/publications of the ATL refer to it by their own word.
Okay, I'm going to ignore your Sarawak factoid straight up because it has no relevance to the discussion about India.
The point is the only reason Pakistan exists is because Britain decided to allow Indian Muslims to form their own state as some (but not all of them!) wanted to. Prior to that time, Pakistan had simply been one of the many disparate region of India and as "Indian"--whatever that meant--as the rest of the parts of the country, a country that had many differences in many areas between them. That was my point. Until the Muslim conquests that started the Islamization of the area, the Pakistan area was essentially united with India. It remained true even afterwards, but from that point on religion began to become gradually more of a divider until the split after WW2. Eventually religion overcame geography, but for the vast majority of the time, geography was determinant. I like balkanized China, but geography is against it. You can triumph over geography but it's not easy.