A concrete example. I see in booklet the name "Steve Arguelle" and I try to find it in MB database (Artist - Search). Nothing similar in first page. Then I add this name as new artist.
Next I create the relationship for the release: "Relate to recordings" and I paste this name "Steve Arguelle" to the search field. But now I see the suggested artist "Steve Argüelles"! Very strange. So I created the artist "Steve Arguelle" in vain, because "Steve Argüelles" already exists.
But why the first search does not suggest the similar name with diacritics (when I type it without them), and the second one suggest it? There are a different searching behaviour?
Surely, only the second behaviour (similar to Google search) is correct.

And now I see that this depends to the concrete letter. When I search "Benoit Delbecq", I see in first line "Benoît Delbecq"! Different behaviour for "i" and "u".