Losing text when editng a PDF document using Acrobat Reader

Good day,

I recently bought the Acrobat Reader software and Im having problems when trying to edit a client's PDF document. The client says the document was generated on a software called Scientific Workplace and is a tex file that reads on latex as well.

I have also noticed that the original font is unavailable on Acrobat Reader so the system has replaced it.

The document has become a mess when I edit; some text is hidden, some text is cut and some of the in text titles are all jumbled up and fall on top of the text.

Please assist, Im at my wits end.

Pho