Spicer translates "feísimos" as "most faithful." This means "ugly," derived from feo, not fiel. The absolute superlative would be "fidelísimo." It is easy to see how Spicer saw a word and mistook it for "fielísimos."
On the other hand, a play on the idea of "faithful" translation?
Spicer has the sense to translated El paseo de Buster Keaton as a "ride" rather than a stroll. You see, paseo can mean a stroll, or a car ride, or a bicycle ride, etc... In Lorca's play, Buster Keaton is on a bicycle. So this simple detail he gets right, whereas many translators unthinkingly call it "Buster Keaton's Stroll." You cannot take a "stroll" on a bike, sorry.