I was wondering how one could go about determining multipliers for the scores in QJM depending on Unit Experience and Training. In Numbers, Predictions & War, I believe thisis incorporated in the CEV score, but it doesn't mention how these numbers were determined, at least to my reading.

Does anyone have a basic idea of the multipliers implied by these effects?

That is an interesting idea, and one I have been trying to use for wargames rules, (ie, how much should unit A's CEV affect their gunnery accuracy, vs their command and contol abilities, morale ratings etc.) However, I believe their is no established methodoligy for doing so. One simply has to make reasoned jugdements based off of what is known about a given force to assign bits of their CEV in this way.
For example, in Dupuy's analysis of forces in the US Civil War, he ascribes the Confederate CEV superiority entirely to leadership, because he felt that their was little difference in the composition of the two armies other than their generals.

Similarly, he ascribes most,though not all of French Napoleonic Wars CEV to Napoleon.

One way of stripping out leadership CEV is to compare, when available, the performance of
two forces of the same nation commanded by different leaders, preferably against the same opposing general. I have been using that method to try to extrapolate separate CEVs for Napoleon vs. the Grand Armee, other Napoleonic forces and generals, and also 18th Century ones.

But that is the state of the art in that ddepartment, as far as I know. One just tries to make comparisions, and factor out similarites, and then try to test your guesses.