As Ynnwns are hybrids of either a Nolthrir or Dermorian with a Diabolo, Ynnwn are fluent in the languages of both their parents. However most adult Ynnwn prefer speaking the language of their elvish parent, be it Nolthrir or Dermorian, rather than the language of their Diaboli parent. This is due to the fact that they don't see their polygamous parent as often and therefore the cultural influence is lesser.
During their youth, however, when living in a location with many other Ynnwn both young and old, Ynnwn will often also use the words of the Diaboli language together with Elvish grammatical rules. This is often referred to as the Ynnwn Language.
Vocabulary is borrowed from the Diaboli Language.
(to be added when we know more about the Diaboli Language)