AFAIK there isn't currently any way to edit the SWB Effects file. For Sims3 a separate tool was made for editing SWB files which later on was included in s3pe.
Certain things can be altered today in a standard fashion. Some of the sound effects are written into XML files, and they can be turned off there or swapped with a different sound. Some of the graphic effects will have a .dds image which works alongside the SWB file; the image can be edited or swapped with a different one such that the 'effect' would look different in game.