Your question is already old a bit. But I had asked a Belgian. He gave me the following information about "Longfaye": The first syllable "Long" is how "long" in English. The second syllable "faye" cannot be translated in German or English. A "Langenfeld" in French would be called "Longchamps"! The second syllable "champs" is in French a field, land. Field is in the German language also a field, land. Therefore you thought of "Langenfeld"? However, in the East-Belgian area around Malmedy the people had spoken never German. Only "walloon"! There are 5 places with the name "Langenfeld" in Germany. In the "Eifel" is a place Langenfeld only nearby the city of "Mayen".