For one, there is no such thing as a triphthong in Latin.
It does look more like a triphthong than a diphthong, but the middle sound is high-central or even high-back.
If two or three strong vowels are together, they do not produce the single diphthong or triphthong sound and are instead pronounced as separate syllables: fea, leo, lee, peleándose and Isaac should be pronounced, Is-a-a-c.
Words such as course and force are sometimes realized with a triphthong //, especially among older speakers.
It does seem that some forms of English have a triphthongal [aI@].
The vowels in fire and power are triphthongs .
In actual words, these unstressed vowels are written ‘i/u ’, ‘e/o ’, ‘a’, ‘ai/au ’, and ‘eai/oau’ ( triphthongal ), i.e., marking roundness but omitting the diacritics placed on stressed vowels of the same quality (since they are redundant due to vowel harmony).
Vowels, diphthongs, triphthongs and consonants are taught using the IPA (International Phonetic Alphabet) for the purpose of eliminating regional characteristics in the student's speech pattern.
Diphthongs and triphthongs do not come into the picture at all.
There is always triphthongal synalepha when a is the middle vowel; or when o or e is the middle vowel, except in the following combinations, aoa, aoo, ooo, aea, aeo, oea, oeo.