This is quite speculative and an area I leave to interested linguists since these kinds of technical linguistic questions are not my main interest.
This has little to do with my syllabic grid in the Ancient Sign Concordance, but I saw this problem and I thought I would mention it.
In Luvian (especially later cuneiform Luvian) one could ask whether the W-based signs, currently transliterated as "syllables" are actually a form of vowel "determinants", which in Luvian would mean that they mark labial, pharyngeal, uvular or velar sounds or something similar, or, possibly mark vowel harmony.
I have read online about "vowel harmony" in the Ural-Altaic languages like Turkish and Mongolian, which I do not speak, so I can not address this issue any further, but vowel harmony could explain the W-based "syllables" in cuneiform Luvian especially, which appear to have been developed to deal with vowel harmony in a language foreign to the original Luvians.
[Here is an updated link to an understandable article on vowel harmony and the languages of the world that have it.]
This would in any case not be an element of the base Luvian Indo-European language and could hence in cuneiform Luvian be a borrowing from Hittite, which I sense to be a Turkish type of language.
Hence, in cuneiform Luvian especially, it might be speculated that the W-based symbols are not "pronounced" per se but instruct the reading of the "modified" vowels in terms of "vowel harmony", where in grammatical elements the subsequent vowel is modified to agree with the vowel of the preceding syllable (base word).
Or, vice versa, someone accustomed to vowel harmony might be trying to write a foreign language using those basic aspects of a language he knows.
That might explain having too many vowels in words the way Luvian is currently transliterated and bring some new insights.
Again, this is speculative and a product of my sensing that original Hieroglyphic Luvian and later cuneiform Luvian are languages that may be wide apart from one another.
LINGWHIZT
