In this case undub means revert the voice acting back to original japanese voice acting or changing localized vocals back to english.
Changing text in menu and ingame is a translation.
I guess you mean to restore rude language from the softer description of a bad word.
The easy way is to get original japanese ("uncensored") version of the game and play it.
I hope i could clarify things a little.
PS2 SCPH-70004 V12 PAL + HDCOMBO + 160 GB Samsung HDD + OPL 0.9.1
PS2 SCPH-70004a V13 PAL Satin Silver
2 x Official Sony 8mb card +FMCB 1.8c + uLE 4.42b
Datel Max Memory 32mb card +FMCB 1.8b + uLE 4.42
Memor32 + Memento FW 1.2e