When we use the command line to generate the pd4fonts.properties file it returns a pd4brower.properties file instead.
During the first run of PD4Browser (java -jar pd4ml(_demo).jar) in any mode, it generates default application properties file pd4brower.properties
You run PD4Browser the first time to generate TTF properties. So it produces two .properties files. One is in the current directory (./pd4brower.properties), another one is in the font files directory (/path/to/my/fonts/pd4fonts.properties)
The fact of two simultaneous .properties files output may be confusing. Also if you generate the properties file for c:windowsfonts, the resulting file exists, but it is not visible with windows explorer (in the folder the explorer in the fonts-only view mode). But the file may be easily opened with any text editor, for instance.
Obviously we need to clarify the topics more detailed in the documentation.