Who, in this comment chain, is making any point about Vedas being purely religious? That is not apposite to this discussion.
The Vedas are a work of knowledge. In philosophy, in natural sciences. There is a strong argument to be made that they capture large parts of the essence of scientific temperament, which is analysis, refection & observation. But, modern scientific research is not just scientific temperament.
Practicing science, modern science, also requires evidence & follows a hypothesis-driven model that makes testable & provable / disprovable predictions.
You seem to be eager to misinterpret OR re-interpret terms to suit your perspective / point of view. "Evidence" based has a specific meaning. This [1] is a reasonable definition of what evidence based medicine means TODAY.
The vedas provide observations. They record correlations (perhaps). That's not evidence!
Lots of work has been lost; that's not unique to the Indian subcontinent. The library of Alexandria was lost. Many of Plato's works are lost. What does that have to do with modern science apart from regret & grief at what was lost?