Jet engines are extremely complex to master.
Only the US/UK/France and Russia has fully mastered them, with China probably joining the club before the end of the decade is up.
India could not realistically have hoped by now to have produced a reliable and powerful enough engine for the Tejas, taking into account its overall technological capabilities.
one needs 3 conditions to make a competitive engine:
1. complete industrial value chain, and a globally competitive one as well.
2. huge amount of inventment across board.
3. sustaining this size of investment for a long time- about decades.
only 3 countries had/have above conditions and could do it after WW2: Britain (had), USA, and Soviet Union.
France got its engine tech from the US.
Germany and Japan, being the lossers of ww2, have not been permitted to have the related complete industrial value chain.
China had almost complete value chain back then, but not powerful and with too little investment.
China started to have the full value chain in the last 10 years or so. Still need more $$$ and time.
India will not be capable of making an engine on its own in the next 200 years, to say the least, because the full industrial value chain is distant dream for India. Talk-show hosts such as heads of ISRO , DRDO and HAL aside, India's current industrial infrastrucutre is next to nothing and mostly at stone age level (e.g. still can not even mass produce with decent quality a post ww2 level rifle or most 101 level ammunitions...).