The text looks like "####" or small empty squares. Yes, you need the pack.
You open a PDF in, say, Japanese, but your Reader interface is set to English. With Smart Language Sync, the Language Pack doesn’t just translate the menus—it intelligently overlays a real-time, non-destructive translation of the PDF content while keeping the original text fully intact and accessible with a single click. adobe acrobat reader dc language pack
The file was screaming in a language his computer didn't understand. The text looks like "####" or small empty squares