I just solved this problem in case anyone else has the same difficulty, and it turned out to be totally stupid brainfart on my part. I had copied over the styles/ directory from /usr/local/share/fluxbox to my home directory. I was editing fonts in the style file in my ~/.fluxbox/styles directory, and had not deleted the original styles directory in /usr/local/share/fluxbox. Fluxbox was using the original style files in /usr/local/share/fluxbox/styles, hence not using the fonts I was trying to get it to use. I deleted the /usr/local/share/fluxbox/styles directory and now Fluxbox looks for the style files in ~/.fluxbox/styles, and is using the fonts I want it to. Now I feel like a total dunce for not working that out earlier, but you get that sometimes.