The way they restrict "false belief" makes the phrase almost an oxymoron. If you "merely accept" that the Earth is a sphere instead of "genuinely believing" it, how is that different from responding yes to the question "is Earth a sphere?", doing your calculations as if Earth is a sphere, making mistakes that reveal that you didn't know the Earth is a bit squished, etc.? All models are false, so either (i) can't be satisfied and must be relaxed, or "technically false" true beliefs are natural and commonplace.

Also, here's my example of an epistemically useful false belief: The idea that there is substance to music theory (more than what you get from a high school education, that is). You will learn a lot of useful things before falsifying it.