Hello:
I can do it by using object navigation.
In Spanish, using VLC 3,0,23,0 (AMD64), the shortcut to open effects is control+e.
Then, I can go to the next object to move to the dialog. Then I go to the contained object, and navigating to next I can press NVDA+enter to enable these features (disabled by default, and then I have gone to the dropdown who shows options like headphones, classic and others. I use NVDA+enter to select. When this is done, I move to save, always using object navigation, and Close. Then I restart VLC and I can hear that effects have been applied.
Hope this helps.
Noelia