Christian, thank you for your comments & suggestions.

<<I wondered whether I would even hear the difference
between a dental and alveolar stop consistently...  but
you wisely chose to use an affricate in the place of the
alveolar stop.  =)  Quite an elegant system, although I
don't share your dislike of velars.>>

I felt that, because this was the first language it had to be
systematic.  Modifications would occur as time passed.  I went no
farther back than the palatals because I did not want to include the
harsher sounds.  At first, I didn't even have the palatals using
instead the postalveolars "sh" & "zh."  Then I decided I did need
some kind of "k" sound.

<<Hehe, a noble cause...  but / are very confusing choices
for an affricate.  If you want to use  in its natural
habitat, why not write /s z/ as | s| (as in German), use
|z| for /t_s/ instead (also as in German) and then maybe
assign |x| to /d_z/ (as in Albanian)?  I'm not sure
whether that would suit your taste, though.  =P>>

My intent was to make it as easy as possible for readers of English.
My present study is aimed at them.  In the original study I use s & z
with acute accents.  And I use an x & a gamma for the unvoiced &
voiced palatal fricatives respectively.  But your suggestions have
merit & I'll give them some thought.

<<Pairing up r with n is really cool.>>

Not only are the points of articulation the same, but there is an
interchange between the two in many IE languages.

<<OK... expect most people to read it as /y/ though.  ;-)>>

In the original study I use an epsilon; easy to write, a tiny
backward 3.  I had originally used e diaresis (as in Albanian), &
would have used it here, but I can't make it!!!  I can make  &
, but not the e or the o.  What is that all about?  I'm using Alt
with the 3-digit ASCII numbers.  Hmmmm, now that I think about it,
maybe  would be subject to less misunderstanding.

<<BTW, what's wrong with not writing epenthetic schwas?
You're under no obligation to present your language in
a phonetic spelling.  In fact, many of us like obscure
orthographies.  ;o)>>

I guess the native speakers don't write it because they know when to
insert it.  Rather like speakers of Hebrew not needing the vowel
points because they know which vowels to use.  In any case, there is
no grapheme for it.  I use one when transliterating as an aid to
who are not fluent in Senyecan.

Again, thanks for your responses.