I'm working with the sketch 61.2. I'm facing a similar issue. I want to get the text layer line height. For doing so, I use
textLayer.lineHeight(), it works perfectly when the user type a lineHeight in the editor panel but return 0 when the user uses the font default font face.
So I try to compute the default line height for the font with a formulae :
font.ascender() - font.descender() + font.leading() but I don't have always the same result displayed in the panel editor. What is your recommendation to get the sketch value ? Maybe I'm missing a Font or a Text property ?