Re: Imported pdf is not readable
This happens when the font to Unicode table in a PDF file is incorrect or has missing entries. You can verify this by opening the app in Adobe Acrobat Reader (and Adobe is the company who invented and defines PDF file format), copying some text, then pasting it in any other app. You will see similar problems in pasted text.
Please open this file using the "Open" button on top of @Voice screen (folder icon), then when the "PDF Text Import Settings" screen appears, enable OCR option in it. This way the incorrect font to Unicode table won't be used at all, instead the letters will be recognized from page images. It will take much longer, but should give you the desired result.