I'm obviously still missing something here...
My understanding is you have 8 audio cues, and you want to map the master slider of each cue to a different MIDI controller.
If QLab were to have that functionality built in you would need a separate MIDI map for every cue to be able to do that. Because QLab doesn't have that capability, you have sensibly opted to use OSCULATOR to convert incoming MIDI cc messages to outgoing OSC messages sent to QLab port 53000
This works well, except there is a delay on the slider levels updating.
If you have 8 cues running you would only be able to see the sliders for 1 cue at a time, and your MIDI cc faders indicate the level of all cues anyway. If you are in show mode you can't see any sliders, so the visual slider update delay won't be a problem
I have attached an OSCULATOR workspace which uses MIDI cc1-8 to control the levels in any cue labelled x.y where y is the point number of the cue to be controlled.
e.g MIDI cc 4 would control the master slider of cues 1.4, 22.4, 999.4 etc.
There is also a QLab bundle with 2 group cues. Q1 has 8 child cues with spoken numbers 1 to 8, and Q2 has 8 choral aahs on different notes.
Using a MIDI controller the response seems immediate, continuous and reasonably smooth.
Doesn't this achieve everything you need?
Mic