Some fonts are created to provide a good output for specific character sets, at the expense of the Latin character rendering in that set. In draw.io you can, attempt to, use any font you wish. Select a shape(s), select the text panel on the right, click the font name, select custom and enter the font name in the dialog.
Since image and PDF export take place server-side, there is a finite set of fonts we support. (Image export is client-side on Chrome and Firefox, so you can use any fonts in those cases). The non-Latin specific fonts that can be used for server based export are (this isn’t a complete list of fonts for these characters, only the really specialized ones for those sets):