Double scripts and slurs

[Maurizio Tomasi]

I think that the PDF file Lilypond 2.3.13 produces with the following 
input has some layout problem:

\relative c''' {
   c8.->-\trill( b32 c)   % 1
   c,8.->-\trill( b32 c)  % 2
   c'8.->-\trill( b32 c)  % 3
   c,4
}

Of the three slur, the first and the third ones seem too high to me.  On 
the other side, I think the second slur is perfect. 

This is not a big problem, as I can fix this by manually overriding the 
slur's extra-offset.  But I want to know if this is this a precise 
engraving choice.

Maurizio.