semivowels

Because of this, a couple sounds known as semivowels are sometimes transcribed as if they were vowels.

However, linguistics has (mostly) reached the conclusion that semivowels are best characterized as consonants.

That's because in the Arabic script, from which the modern Persian script is derived, doesn't differentiate between vowels sounds like oo/oh and their related semivowels.

Phoenician semivowels waw and yodh furnished upsilon and iota, respectively.

It is not apriori unreasonable to consider semivowels as vowels.

The fact is that language is itself not symmetrical (consider 5 major vowels vs 21 consonants and semivowels), so really a better solution is to use a keyboard layout that is optimized to fit a physical arrangement of keys.

The Egyptians marked semivowels /j~i/ and /w~u/.

On the one hand it is laid out logically with voiced and unvoiced consonants each in their own rows, vowels are neatly placed on one side, the semivowels have their corner, etc, etc.

Thus the vowels are subdivided into simple vowels and diphthongs, each set up as short/long pairs (a-ā-i-ī-u-ū, etc.), while the consonants are classified into the groups vargīya (comprising stops, sparśa, including nasals, anunāsika), antaḥstha (semivowels), and ūṣman (spirants, including ha).

The technical term for W [w] and Y [j] is "semivowels" (or "glides"); they are pronounced like vowels with no obstruction of airflow.

Semivowels don't usually give rise to any uncertainty regarding syllable boundaries.