I played around with your file a bit more. Try this:
1. Select the whole thing, and open the Hard Limiter module.
2. Set your dB limit to -24, Wet level 1.0, Residue level 0.2.
(Note - the dB limit takes a bit of trial and error to make sure your limiting what you want but not harming the music. Residue level controls how "hard" (low number) or "soft" (high number) the limiter is. See the quote from the manual below for more info.)3. Hit OK to accept the changes.
4. Again make sure everything is selected, then go to Effect > Normalize. First two boxes are checked; third is not. Set your max level. I leave this at -0.2 dB though if you're going to do additional effects or processing some would prefer lower.
Banshee lady should now be about equal in level to the highest peaks in the music. To reduce her any more, you'd probably need to split to two mono tracks and try further limiting on the left channel, as that appears where she's hanging out most of the time.
From the Audacity manual pages:
==dB limit==
The level above which the input signal is processed. If the Wet level and Residue level settings are left at default, the peak level of the result will be clipped down to this level.
==Wet level==
The amount of the clipped signal that is fed to the output. It thus acts as a volume control for audio below the dB limit. If left at default level of 1.0, all sounds below the dB limit are fed to the output. At settings below 1.0, the volume of the result will be reduced.
==Residue level==
This allows a proportion of the signal that has been removed by clipping to be added back to the output. By default the value is 0.0 and so all of the clipped signal is discarded. By raising this level, some of the clipped signal will be restored, making the limit softer. More peaks and troughs of the original waveform will be retained, and the resultant volume level will be higher than that set in the dB limit.
{{Note|'''Special effect:''' If you turn the Residue level full up to 1.0 and the Wet level full down to 0.0, you will hear only the pieces of waveform that are above the dB limit you choose.}}