The reason for the error is that there are defined actions and triggers that reference the difflevl symbolic table, which doesn't exist. BG2 had the same problem with shoutids and moraleai, and IWD had the same problem with diffmode/difflevl. Almateria's right that it's a harmless error since nothing uses a symbolic compile with those triggers; that being said I went ahead and included difflevl/diffmode in the IWDFP because I got tired of seeing the warnings.