Hi,
This is actually already a proposal: https://wiki.openstreetmap.org/wiki/Proposal:Flight_School
There are lots of things to think about and discuss when making a proposal, as can be seen on the discussion page. Please feel free to read up on OpenStreetMap tagging, the proposal process, and familiarize yourself with the topic if you want to contribute to this proposal being approved! It's certainly possible, and it would be great to have a global standard for flight school tagging!