I think a great deal of care is needed with this "issue".

As I have said before, Norwegian has three unique letters that go at the end of the regular latin alphabet (æ, å and ø), and are considered individual letters (ie å has nothing to do with the letter a).

Swedish also has three unique additional letters å, ä and ö, again, these letters appear at the end of the Swedish alphabet, ä and ö should not be confused with the German use of umlauts.

Additional, the original post mentions Arvo Pärt (an Estonian composer). The Estonian alphabet has three vowels with umlauts that although based on the German, are considered letters in their own right and belong at the END of the Estonian alphabet. In gurnemanz's example Pärt is correctly located between Prokofiev and Quink!!

Andrei, I think you need to be very careful before implementing a blanket "fix" on this, as you could end up doing far more harm than good!