Enoki
SOC-14 1K
Absolutely. Maybe score it 1 to 10 in difficulty and 1 to 10 in difficulty for a native or species that is closely related. Something like N 1 -10 A 1-10 where N species are listed and all other species are in the A category.I would consider that language difficulty would also have to be gauged relative to the species in question (i.e. Trokh ("Aslan") and various dialects of it might be easy to average for an Aslan, but very difficult for a human or Vargr (and vice versa), due to the difference in mouth and vocal arrangements/tonal range of the species. Perhaps even the ability of the ear and speech-centers of the brain might make meaningful comprehension between different species difficult due to what each brain is hardwired to hear and interpret. OTOH it might be possible that one can understand a language but be physically unable to speak it (and vice-versa).
Depending upon how granular you wish to be, you might wish to allow languages that have a common-root origin to be easier to pick up if the speaker knows a language in the language family or subfamily. For example, I would guess that it is probably easy for a Swede to learn Norwegian, Danish, or Icelandic, somewhat more difficult to learn German, more difficult to learn English or French, and a lot more difficult to learn Korean.
Vargar would be one. The language of a Cytrialin where you have two distinct species that interact symbiotically and with some degree of psyonics involved would be another even as the spoken language is a derivative of Vilani. Aslan would be a third.