Hey deadL - lets reduce the complexity and focus on 1 task at a time.
1 texture + distort by noise + custom vertex stream fade
note UV0 split-> (Blue) corresponds to [custom1.x] on the particle system
UV0 Red and Green channels in the setup are reserved for actual UV space (not customizable)
the custom1.x curve will drive distortion over time which is added → UV → texture
result at 0.1 seconds
result at 0.75 seconds
clearly the distortion has a bias; as the cumulative values > 0 move down left
let’s offset the value so that it is 1- to +1 and 0 acts as the middle
here is the result at 0.75 seconds - everything is more centralized
does this help you understand how to implement the concept better?