Ironically, the diaeresis which it probably ignored is essentially an indication that the two adjacent vowels do not form a digraph and hence form parts of two

Ironically, the diaeresis which it probably ignored is essentially an indication that the two adjacent vowels do not form a digraph and hence form parts of two syllables. (Admittedly, umlauts and diaereses are represented by the same characters on a computer, but their placement with respect to other vowels gives them away most of the time.)