I think the problem is with the concept of default in this case. The default should be the basis for a specific tailoring, and as a last resort for scripts and letters that do not have specific weights, but each implementation should have it's own weights when it matters. Only rarely is the default useful in itself, except possibly for Latin based locales.
For example, a Israeli oriented tailoring would cause Hebrew to sort first, Arabic, Latin and Cyrillic to follow in whatever order is desired by the user, and other scripts would follow in the default ordering. I am not sure that the current default makes this task possible or easy. Jony
