There was that incident a while back where a bunch of government leaks were outed as fake because they were printed with a (default MS Word) font that was not available or in use when the document was purportedly created
Then Pakistani Prime Minister Nawaz Sharif tried to cover up a scandal that was revealed in the Panama papers back in 2014. He forged a document purportedly from 2006 using Microsoft's not-yet-released font Calibri as an attempted cover story.
Do you have real-world examples of the hypothetical you invented?