Hinduism was never as huge in Sindh and Punjab as you state that it was. Sindh has more historical Buddhist Stupas and other Buddhist structures than Hindu structures. Almost same is the case in Punjab and KPK. The Arabs in Sindh in 712 AD were supported by Jats, Meds and Buddhists who were in majority against a Brahmin Raja who was a ruthless tyrant.
Lahore had different names in different times and because Indian Hindus beliefs that it was named after Lord Ram, let it be. It does not in any way undermine the fact that Indian Hinduism was never popular since the earliest times and this is a historical fact.
There are many many Hindus who believe that Rig Veda is monotheistic in nature. If at all there any delusions, these are Indian Hindu delusions of Hindu grandeur that never was.
And you know where Buddhism came from? INDIA
You do know the blue wheel in the Indian flag is the only religious symbol we have in our flag, and it happens to be a Buddhist symbol...
As for Lahore, you are just making up BS. And why was the biggest city of Pakistan named after the son of Bhagwan Ram if as you claimed in the begining, did not have any connections to Hinduism? Tell me what other meaning does Lahore have?