Go back to King Cut. Try to split the track in bands in your head, and ask yourself can I hear it for each band. When you've gone through all of them put your mouse on the one you think is missing, and turn off the eq (left arrow). Try to make an imprint of the sound of the band that was added back in. Repeat.

To practice go to the practice mode of Kit cut. And to improve in the Olympics it helps a lot to use the arrow keys and the mouse at the same time, this way you can listen to the missing frequencies and your brain will memorize little by little.

The current edition is a quite challenging one, so it might not be the best situation to draw conclussions about your EQ skills. The same solo voice in every sample and the narrow band for detection make this exercise hard as hell, at least for me!

@Cuantas Vacas I imagined something a few days ago. But I find it really frustrating to have made so little progress despite the various attempts I've made. I managed to improve something a little while ago, but I'm not entirely sure if it was due to pure luck or an improvement in my skills.

Santi Rod, to heare Subtractive EQ more more difficult then Additive EQ, and developing this skill gets more time.
so must important advice here - keep calm, and regular practice )

u already have good suggestions from other colegues, and u should take it.
only thing I want to add - if u on PRO account, use function change level in Kit Cut gym, and lower the level as it posible (max 10). do trening on it level. and don't rush to up. go up slow.
and when u feel stuck - go several levels down again (it work in any other gyms)

ps by the way, what level Kit Cut you on now?

@Vitalii Mizhenin 15 at this moment :-)

I've noticed some improvement today, but I'm still having trouble recognizing around 1,000 or so. Maybe next time I'll see a bigger improvement. Thanks for all your suggestions.

15 it's not bad!
but try turn down level, and try every other time take game without switching on/off EQ

@Vitalii Mizhenin I'll try. Thanks!