Some languages use a script that requires a vertical spacing between lines (line height) that is larger than the default setting. Otherwise, tall characters may appear too close to characters in other lines. In other cases, such as Devanagari, the vowel symbols above a solid line may not fully appear on the top line of the text box.
Using the Book Making tab lists the steps you need to do.
Styles can have also different line spacing. Names of styles you add should distinguish the styles to indicate their intended use. Use the Format dialog to configure styles.
http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id= can help you find the font you need. You can search for information about a specific language.
For example, http://scripts.sil.org/cms/scripts/page.php?item_id=ArabicScriptFAQ&highlight=Arabic discusses Arabic scripts.