Like many other commenters, I am also not sure why you’d want “katsu” transliterated to “cutlet”, but the author didn’t choose to have a tool to do this out of ignorance of the Japanese language.
Regarding the name, it's true that the word "cutlet" isn't typically an example of where you'd want to use the foreign spelling functionality. However it had several other nice points:
1. It follows the tradition of naming Japanese language tools after food the author likes, like MeCab, Sudachi, my own fugashi, etc.
2. It has a concrete image that's easy to convey, which is useful mnemonically
3. It's a very clear demonstration of the foreign spelling feature (even if not a useful one)
4. The word "katsu" is a good example for showing the difference between Hepburn and other romanization systems (katsu/katu)
"The cutlet was introduced to Japan during the Meiji period, in a Western cuisine restaurant in the fashionable Ginza district of Tokyo. The Japanese pronunciation of cutlet is katsuretsu.
In Japanese cuisine, katsuretsu or shorter katsu is actually the name for a Japanese version of the Wiener schnitzel, a breaded cutlet. Dishes with katsu include tonkatsu and katsudon."