diacritic (Hebrew nikud) not well positioned

[Yotam Medini יותם מדיני]

In Hebrew Lyrics, frequently diacritic (diacritical marks) 
are not well aligned with the letter they should be attached to.
In Hebrew they are called 'nikud' or 'niqud' and are used as vowels.

Attached are example files of Lilypond source (\version "2.10.33")
and an annotated screen shot.
In that example, The Patah diacritic which is like an underline
below a later
  Unicode= U+05B7 : /afii57798 : HEBREW POINT PATAH 
  http://unicode.org/cldr/utility/character.jsp?a=05B7
appears 3 times:
+ On the left side, it is slightly right to the (Kaf) letter
+ In the middle it looks well aligned below the (He) letter.
+ In the last right side it is almost detached - right to the side
  of the (Vav) letter, while it should have been below it.

Since I am well experienced with C++ and gdb, though not in Pango and Guile, 
if someone can point me - where in the C++ code this offset is being
determined, I may try help solve this issue.

Note: In modern Hebrew text, diacritics are rarely used.  But with
music notation, they become essential especially for 'prima vista'
singing.  With the almost impossible mix of left-to-right music and
natural right-to-left Hebrew, it is difficult in many cases to guess
the right vowel without diacritical mark.  This is because the natural
right-to-left Hebrew context is lost.

-- yotam

nikud.ly
Description: Binary data

nikud-bug.jpeg
Description: JPEG image