Herbert supposes the diphthongs to be "the first perhaps used in this kingdom."
If they appear as proper diphthongs, they follow the rule of diphthongs.
The nasalising of these diphthongs adds to the unpleasant effect.
All words have as many syllables as they have vowels and diphthongs.
There are as many syllables in a word as there are separate vowels and diphthongs.