Suggestion: Adding Keyword, or SearchTag field, do you agree or am I alone on this

As already told here:

You can add as much Tags, "Keywords" or "SearchTag" fields to your music tracks as you want.

The problem remains the same:
All the App developers are using the de-facto standard fields from id3.org.

Sorry to say, but I rate your chances to get some "Keywords" added and supported by nearly all apps, players and devices out there at practically zero.

Another idea:
Maybe there are some Music Management Tools out there where you can add such additions and then search in this 3rd-party-app for your "Keywords". This app would then save your information in its own database, not in the tracks itself.