Dear snl_,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
As per your description, please don’t worry, we can work together to narrow down and resolve the situation.
As you mentioned, " but still "English (U.S.)" shows up in my languages in Word" I suspect the problem occur because there is English languages shows up in Word.
First, please allow me to explain, the language is a property of the text. If a language attribute has been applied directly it overrides the Style. Select all (Command+A) then change the language attribute by going to Tools> Language or by using the Language button on the Review tab.
If possible, could you, please disconnect your printer from your device//Mac OS and then try to exporting to PDF file format and verify the result with us.
Also, to check if this problem is related to Word app itself when save Word file into PDF file format, if possible, could you please try go to Word for Web, login with your Microsoft Account and save your Word document as PDF and verify the result with us.

Since you mentioned, "my colleagues experience the same" to confirm whether this is a bug in a specific version, please provide us the version information of your version of Mac OS and Office
Find out which macOS your Mac is using
About Office: What version of Office am I using?
Your understanding and patience will be highly appreciated. I hope that you are keeping safe and well!
Sincerely,
Waqas Muhammad
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