If you want the small signs to be on the baseline, type
\SurLigne out of a hieroglyph environment; the default is to
center signs. To switch back to centered signs, type \Centrer.
In a cartouche, the text is always centered. You can handle the
line-cutting algorithm by changing the two TeX macros
\Hrp and \Hitmts; the first rules what is
inserted between signs, the second between words. The default values
tend to protect you from cutting a word, at the cost of some white
space.