Why do they need tender for even this thing??
Give direct contract. Indian HSR line is totally Japanese gauge and tech so only Japanese company will supply the train sets.
Tender is to select the Indian partner. It's not that trains are going to be built and transported to India. It will involve some screwdriver-ing tech like assembly, maintenance, installation etc. All of these things require an Indian partner company.
Also, post Rafale fiasco, procurement of high value items without adequate tendering process is frowned upon and is permitted only in the rarest of rare situations when the product in question is very high tech, research oriented, and one is not freely available in the market.