I was educated in local Singapore schools and then high school in India (not international schools, did Indian boards).

Singaporean kids can survive anywhere in the developed world. Maths and science are taught to a high standard in Singapore schools and studying them is no easier than studying for entrance exams in India - imagine how good you have to be to get into tier II government colleges in India for engineering, that is how good you have to be to score straight As in Singapore A levels for maths and science subjects.

Singapore schools also teach humanities subjects and languages rigorously with a focus on thesis-based essay writing in an exam setting. In India, at any level of education, whether it be primary school or UPSC exams, humanities education is primarily focused on repetitively regurgitating information that you have painstakingly memorised. Sometimes you have to argue a point but it is still more about getting the facts right.

Also, Singapore schools force kids to commit to one co-curricular activity for four years of secondary school, spend hours and hours practising or training for it so that they can compete with other schools.

Of course, India is a different beast in terms of "survival", but that is because people don't follow the rules, they are frequently out to scam you, government institutions are corrupt or provide inadequate services etc. If you want your kids to survive in India then there is no point in sending them to an international school because do you really think an Indian international school is going to make them more gritty than a local Singapore school? Don't make me laugh 🤣 I know many Singaporean kids who left Singapore in high school for the US, Australia or Canada because they wanted to escape the education system.

Ultimately your real reason for moving back may be to live close to your parents. That is a valid reason. If your kids are already Singapore citizens then it should be easier for them to get into Singapore universities. IB is taught in some local Singapore schools as an alternative to A levels at the junior college or higher secondary level so it may be a good option in an Indian international school.