They do not have a plan to track DEX trades. The only way they can get the trading data is through the Indian exchanges running from Indian soil. It has been made mandatory for all users to complete full KYC and every single data to be transmitted to the government and Income tax department. That's why I was always very vocal against using India crypto exchanges. You would have no privacy on your crypto holding.
I don't think Indian government would reconsider this tax. Because the Finance ministry is seeing huge pressure from the banking lobby to completely ban cryptocurrencies in India. We all were expecting the same but never though that they will come up with 30% tax and no loss offset. They will probably wait for one or two years to see how much tax crypto is generating before taking a final decision on banning it! I mean, that's what we can expect from a regressive government!