French and Italian publishers (and composers) have not usually used hyphens to separate syllables in lyrics (the same is true for German in older editions from Breitkopf & Härtel).
What symbols have people been using when setting French in Dorico? It’s difficult to find anything suitable and the positions can’t be edited.
The following is from the 2014 Peters Urtext edition of Fauré’s songs. It shows the use of an unknown symbol dividing the words into syllables, an undertie to mark the elision of the final e of appelle, an extender line after nuit, and a true hyphen for rends-moi.
They’re more like the width of an en dash but much closer to the baseline.
I’ve looked at a large number of scores over the past twenty-four hours (everything from Berlioz to Boulez) and no publisher has used hyphens. It’s also clear from looking at autograph scores that composers have expected a dash close to or on the baseline.
Duparc’s manuscript for L’invitation au voyage is particularly neat and given that he’s actually drawn a line across each system for the text, it’s clear that he expected a dash on the baseline.
I’m not sure one can duplicate these scores in Dorico unless one tinkers with the font.
Frankly, I’m really unsure why you would want to use anything other than a hyphen… The words are, in fact, hyphenated, even if you substitute an other symbol. At least in the example shot, it just looks wrong: as though the alignment was screwed up accidentally.