Checked and confirmed, even Dutch digraph Ĳ is folded properly, as well as the upper case dotless Turkish i and the Spanish example you provided is folded properly.
Correction for German (before Nagel corrects me), ö and ü are not normalized by ICU folder according to German rules. Their accents are stripped instead of transforming them into oe and ue respectively. It makes the case of language specific folders, especially when dealing with Scandinavian or German. Dutch and Latin can be folded just by removing their accents.
Correct me when im wrong!