Adobe Acrobat DC Text looks like a bunch of squares and and junk

Are you using Preview, or Adobe Acrobat Reader? In the past, Preview has had problems with certain types of editable forms downloaded from Government Web sites. (If I'm not mistaken, there was another recent thread where someone reported a bunch of black boxes where they had typed in their tax data – and that person was using a modern version of macOS.)

Try installing the free Adobe Acrobat Reader, and using it to edit fresh copies of the troublesome forms, making certain not to open those forms with Preview for any reason. See if that works around the problem.

https://www.adobe.com/acrobat/pdf-reader.html