Script Studio fully supports Unicode text input and complex word forms for foreign languages but you may need to install a specific font that supports all the glyphs in your language's character set in order for your text to display, print and export to PDF correctly.
Some fonts such as Times New Roman handle most characters in all languages and/or use a process called glyph substitution but other fonts do not and so sometimes display question marks or outline rectangle boxes for glyphs they do not understand.
Print To PDF
If you are using an appropriate font but still have trouble exporting your foreign language document to PDF then there is another easy solution.
On Mac you can simply select Print and then Print To PDF.
On Windows you need to download a PDF Printer Driver, install it and then select that printer driver when printing instead of your default printer.