On the Term "Commercial Use" and the Usage of an Apparently Free Font

Question

I am in the process of finishing up a book which I anticipate will be published in the United States.

For the book's cover, I would like to make use of a font that is freely downloadable; and, as far as I can tell, does not forbid commercial use. In this case, I would like to make use of a font available from https://www.schäffel.ch/de_gruppe1.html.

Now, I say, "as far as I can tell", for German is not my native language, and although I did not determine that "commercial use" is forbidden, I also did not detect anything along the lines of "free for commercial use."

QUESTION: Would using a freely downloadable font for a book to be published be considered as "commercial use"; and if so, may I legally use a font in that book (without reprisal) from a foreign site, which again, "as far as I can tell", does not seem to forbid it?

Answer 1

https://www.schäffel.ch/allgemein_de.html:

"Die Fonts dürfen für private und professionelle Zwecke unbeschränkt verwendet werden. Sie kommen vollständig und mit allen Einbettungsrechten. Es wird gebeten, jegliche Modifikation der Datensätze, den Vertrieb unter anderen Namen, die Verteilung auf anderen Websites als dieser oder die Eingliederung in Font-Pakete zu unterlassen."

That is,

The fonts may be used without restriction for private and professional purposes. They come complete and with all embed rights. Please refrain from any modification of the data sets, distribution under other names, distribution on websites other than this one or incorporation into font packages.

Answer 2

Lack of prohibition is not permission

The way copyright works is simple: you do not have permission to use the font, therefore, use is only permitted if copyright law allows what you want to do. The fact that the copyrighted work is publicly accessible does not amount to permission - even if it was posted by the copyright owner, which, of course, you have no way of knowing it was.

In the US, you are allowed fair use. This is a case-by-case 4-factor assessment. Commercial use counts against fair use but it is not, on its own definitive. Non-commercial use counts for fair use but, again, is not definitive.

You need to either find the copyright holder and obtain permission (on whatever terms they agree), or you convince yourself you use case is fair use and defend that position when you get sued.