Modelling inductive and capacitive coupling in LTspice
The only possible suggestion I would make is to reduce the coupling factor in the transformer from 1 to something much smaller. You could even go on to use two pairs of coupled inductors fed from the same interfering source feeding each individual wire then changing the coupling facts also introduces a differential noise.

For C1 and C2, it is likely to be tens of pF rather than tens of nF.

You can also use .define statements to ratio the values of C1 and C2 so that in total they add up to (say) 20 pF but  have different values automatically like this: -

.define C1val 10pF

.define C2val 20 pF - C1val

Then for the actual values of each capacitor instead of each being 10 pF, they assume the value "C1val" and "C2val"

So, if you redefine C1val as 5 pF, C2 val becomes 15 pF automatically.