Maybe this could be a very effective and also easy implementable idea. It could be also possible that I still missing the fact that this is already possible by changing the sequence of the modulators with a modulation set…
What if the Renoise team would add bracket operators to the modulation section of the sampler editor?
Currently it’s not possible to realize two independent influences on the same target of the same sample at the same time! At least I could not figure out how to implement this.
Example
Take this song/instrument: Simple PWM test in Renoise 3.0
Now imagine how you would add also an independent vibrato to both sample layers (especially sample 2), that will slightly fadein after 500ms?
Or is this already possible? If so how?
Imagine now, you could set a opening and a closing bracket: You could calculate the detune stuff first in the first set of brackets and then add the vibrato in the second set of brackets.
Like this:

BRACKET OPEN
pitch operand 
pitch ahdsr
BRACKET CLOSE 
BRACKET OPEN
pitch lfo
 pitch fader
BRACKET CLOSE
So the left column of a modulator which currently contains +  * / should contain two fields ( and ) from which ( is selectable at the same time.
So possible combination would be:


 / +( ( *( /( )

Could be also implemented with some sort of grouping…
EDIT: Maybe just follow math rules?
If the modulators in the chain would follow the math rules that multiplication comes before addition, in my example brackets would not be needed.But it does not seem so. The modulator seems to be calculated on the sum of the modulators before.
So it would maybe simply help a lot, if modulators that are “connected” by multiplication / division will be calculated first, and then addition / subtraction of results and modulators.
Take this example: Simple PWM test 3
See sample / modulation set 2: I want to add the vibrato that fades in after some time. Currently impossible?
Calculation in pitch set 2 currently seems to be:
(Operand + pitch ahdsr + pitch lfo) * pitch fader
If following math, it would be:
Operand + pitch ahdsr + (pitch lfo * pitch fader)
Is there any case, following math rules would limit the current possibilities?