Keeping the semivowels Y and W

                            A-ko              E-ko                   I-ko                      O-ko                       U-ko               

I'm now inclined to think that I should keep y and w as the semivowel equivalents of i and u. For one thing, it's often difficult to determine pronunciation when i and u are used for both. How do you pronounce this?:

uia

OO-yah or WEE-ah?

So if:

y=/j/
w=/w/
q=/N/
c=/S/
j=/Z/

that only leaves x to assign a value to. Should it be a modifier of other characters, as it has been in the past, or should it stand for schwa. I think I should keep it as a modifier, and find something else for schwa. Lojban of course uses y for schwa.

I do want letter name for all but the vowel be the letter plus schwa sound, as I believe is the case in Lojban.

Any thoughts on using an apostrophe for it?
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Late-breaking news. I just remembered that Gua\spi  [link] uses # for schwa. If I did the same, I'd still have X as a modifier for other letters. Thoughts?