[Turtle91]

There shouldn't be a problem with a font-family reference. The problem ePubcheck would have is the @font-face that is left behind referencing a resource that is not found. That generates an error.

@font-face {
    font-family: RandomFont;
    font-weight: bold;
    font-style: normal;
    src: url('../Fonts/RandomFont.ttf');
}