Open up update6.rpy, edit->search: "[d_word]" change to "[d_name]"
i used your update6.rpy file and i deleted the update6.rypc, so there is no [d_word] left in this rpy.
so now in the file i have
chieves.append("Finished watching [d_name] change clothes without interruption.")
achievement.register("Finished watching [d_name] change clothes without interruption.")
but, in game, i can't make that event happen (still wondering which on it is, is it the one when she changed herself in her room after i bought the clothes ?)
and when i wrote completeAchievement("Finished watching [d_name] change clothes without interruption.") nothing happen. i tried by replacing the [d_name] with the "real" name too.