Yes, I knew that warning and inserting the spacing item padding was the first
thing which I tried. However, without any success - the insertion of the
line
\once \override Score.SeparationItem #'padding = #3
into the music is ignored by the spacing engine. Using still the same
example as above, the code here replaces only the variable notyOKriste:
notyOKriste = \relative c' {\time 12/8 a'4 c8 a4 g8 f4 e8 f4. c'4 d8 f4 e8
d4 bes8 c4 c8 d4 c8 a4 d,8 f16[ \melisma e d8 c] \melismaEnd
\once \override Score.SeparationItem #'padding = #3
d4. \bar "||" }
I am rather new to Lilypond and therefore I always try to think first that
the error is on my side - perhaps I am inserting the separationitem code
into wrong place...?
However, the syllable alignment which overlaps the neighboring note problem
is most probably a bug: since the code of the lyric spacing is already
present in Lilypond, and since it does not produce the desired output, I
still think this issue qualifies as a bug in the strict sense of the word.
I tried also the trick with the null markup on the last note of the melisma
with the melisma ending just the note before as suggested by Mats, but this
code does not work on my setup. During the compilation, the Lilypond stops
at the line Analysing... and produces nothing (but still giving no error).