thanks for bringing this up because i also intended to ask about what seems to me india's curious aversion from pursuing aeroengine industry. i think any student of aeronautical history will quickly realize that engine technology is one of the most critical and foundational pillars of aeronautics. and like you point out, the indians should have learned this lesson themselves a long time ago when all the engines the marut was designed for fell through. in contrast, the turks understand that their indigenous kaan needs an indigenous engine, and its already been justified by the recent us denials to engine deliveries for turkey.
The irony is that the Indian-made helicopters that kept crashing in Ecuador are named Dhruv (lit. "Unshakeable")
I'd argue the HAL Marut, despite being unsatisfactory, was more successful than the Tejas. Atleast it got manufactured in decent numbers and experienced operational combat.
The idea of Kaveri seems reasonable. I think what is missing was the entire industrial capacity behind it - the techs itself, material sciences, electronics, internal components, etc - they are not up to par yet.
This was the time when india SHOULD have put some money-no matter how difficult- into developing/finish developing that engine-imagine the success and ecosystem that would have been developed over 50 years but now after that missed golden opportunity the frantic bleatings/hysterical wailings about joint-ventures and transfer of technology isn't going to happen and isn't RAM coatings significant as well as geometry/shaping -IIRC it isn't just 1 thing only,i.e the 5 "S"'s of 5gen stealth.
This is absolute clownery. The hard part is not knowing what's in it. The hard part is mass producing those things with low failure rates.