Since the Windows 10 fall creators update all files with the Symbol standard 14 font are no longer rendered properly. Seems to have something to do with a difference in the cmap subtable (all numbers start with F000) and a missing postscript table.
The font has two cmap subtables. The first one has codes that start with 0, the second one has codes that start with 0xF000. The code names we get from getUniNameOfCodePoint(unicodes.codePointAt(0)) are NOT the low ones, only some match, those that are also in ascii.
For ">", there are two cmap subtables codes: for "Macintosh, Roman" it is 0x3e, for "Microsoft, Symbol" it is 0xf03e. I tried forcing the first table
cmap = cmapTable.getSubtable(CmapTable.PLATFORM_MACINTOSH, 0);
but many codes are missing, e.g. the greek alphabet.
For "eta" (looks like an "n")
pdf code 0150 = 0x68
windows code in charmap.exe: 68
code in subtables: 0x68 and 0xf068
pdf code 0340 = 0xe0
code in subtables: 0x0e and 0xf0e0
So it seems one has to bypass this unicode thing and work directly with the symbol encoding...