So long as the word "Accounting" is text and not a GIF, JPG, or PNG of the word, DLP (Prevent for Web, or Prevent for Email) should be able to detect it. It doesn't matter if the words are in headers, footers, or the properties of the document.
But also note, it doesn't know the difference between the header text and the document text. Nor does it see the differences in fonts. To DLP, the entire document is one document. So if you tell DLP to look for the word "Accounting", it will find it anywhere in that document, no matter what font, size, color, etc.
Someone else may be able to help figure out if DLP Endpoint can tell the difference.