However, I’m running into an issue. Whenever I open the generated Word report, I receive a warning: "Unreadable content in the Word file."

Are you able to share a minimal demo that creates "Unreadable content in the Word file." We would look what can be wrong.
https://playground.jsreport.net/

Any insights on how to achieve both Word and PDF outputs ?

You have two options...

You define two templates, one using docx recipe to produce word document and one using chrome-pdf recipe producing pdf from html.

Or you use unoconv extension, which uses libreoffice on background and converts word to pdf.
https://jsreport.net/learn/unoconv