Realearn and "Enable only when effect configuration is focused"

I am trying to set up a MF Twister with ReaLearn. I have mapped controls to a delay plugin and saved it as a preset and that part is all working fine. What I am now trying to do now is find an equivalent to the "Enable only when effect configuration is focused" option in standard MIDI learn. I am finding the documentation very confusing. Please could anyone explain the next steps I need to take to achieve my goal?

The target option "FX must have focus" should roughly by equivalent to REAPER's "Enable only when effect configuration is focused". Do you see it? But most users want way more than that. They want the controls to change depending on which FX is in focus. If you want that, consult section "5.3. Using "Auto-load" to control whatever plug-in is currently in focus" in the ReaLearn tutorials chapter.

Are running ReaLearn on the monitoring FX chain? Or maybe even one of the FX that you want to control?

I'm running ReaLearn on FX Monitoring and the effect itself on individual channels.

That is brilliant. It's now working exactly as I hoped it would. This is amazing. Thank you so much!!!!