Hello sigpark,
I changed the skin and for the editing, I can use now the E2 skinner. For this, I use a trick: I delete the "Aliases..." part of the fonts in the skin.xml. After editing the skin with the E2 Skinner, I do back this part to the fonts. You can not see the .otf fonts with the E2 skinner, but it works. Greetings.
"<!-- Aliases that should be present -->
<alias name="Body" font="Regular" size="20" height="25"/>
<alias name="ChoiceList" font="Regular" size="20" height="25"/>
<alias name="TextNormal" font="Regular" size="20" height="24"/>"