While validating all the fan ages available via UAM with libHSPLasma ("validating" as in "read & parse and look for errors or warning"s), I stumbled upon the same message in various ages (for example Camp Bravo and Prad):
[0079:<name>] Size-Read difference: 2 bytes
0079 is the type ID of plRandomSoundMod
Looking at the source code of PyPRP, libHSPlasma and Drizzle, the latter two expect the size of the array in that class to be a 2-byte value, while PyPRP uses the hsTArray.write function, which results in a 4-byte length value. I can't tell which one is correct, but since libHSPlasma reads all POTS ages without warning, this looks like a bug in PyPRP for me.