Hard to be sure without seeing what’s going on, but I suspect the useless faders are for MIDI Control Data and not Audio.
There are 2 types of Tracks in Cubase that can Play MIDI - MIDI Tracks and Instrument Tracks. It is very worthwhile to read the Ops Manual on them to understand all the differences.
With MIDI Tracks you have to load a VSTi into the Rack as a Rack Instrument (not Track Instrument) and then in the MIDI Track’s Inspector assign the Track’s output to this Instrument. So the sound doesn’t come from the fader(s) with the Track’s name but instead from the fader(s) with the Instrument’s name. Initially this was the only way to use MIDI.
Managing all that for a bunch of Track’s can get tedious and create busywork so Cubase eventually introduced Instrument Tracks which are like a MIDI Track and a VSTi combined together. So you don’t need to care about the behind the scenes routing of MIDI data to the VSTi. With Instrument Tracks the fader in the MixConsole will have the same name as the Track.
MIDI Parts can be dragged between the 2 Track Types without issue.
I’m guessing you are using MIDI Tracks that are not connected to a Rack Instrument.
Make sure the Routing section in the MixConsole is visible so you can see what’s routed where. Also those provided templates are best used as starting points. I’d encourage you to create your own customized Templates as needed.