If you want to, you can download, check it with your anti-virus, unzip it, un-FPKpack it, take the two DDS files into DXTbmp, save the BMP versions of them and see what they look like.
That would spoil the fun.
DDS files in Pirates! only change the graphics.
I wonder how one could use this to cause the program trouble.
BTW the mods are at most P-G rated (being excessively conservative here) and if you are still suspicious, you can unpack and examine the files to ease your suspicions.