You would think that it would work that way if two plants are genetically compatible, that the same cross could be made either way. In my experience I'd say not always, that napaulensis cross was repeated in six different combinations, crossing napaulensis pollen onto Lingholm, baileyi and grandis and then vice versa, with a few extra attempts included to make sure that I got the best possible chance of getting a successful cross. However even with all that work, only one of the crosses actually produced fertile seed and I am pretty sure that was with pollen put onto napaulensis most likely from Lingholm but until I find these missing transparencies I won't know for sure.
Sometimes one plant might work better as a seed parent rather than pollen parent, this is usually the case with Lingholm for instance, it gives good hybrid seedlings but there is nothing to stop anyone from doing the cross in the other direction. The only thing which matters is the end result in any case! I would tend to try every cross both ways as a matter of course and even if you get a decent F1 generation seedling, it might still be worthwhile to try to self pollinate those seedlings and raise the F2 generation. Reason being in my view is that under normal circumstances certain genes are dominant in any true breeding species or form, when you make a cross onto another true breeding form you don't know for sure how the seedlings will turn out. Usually they will be fairly similar but one or two might be exceptional and the rest just fairly good. With the F2 generation you may well get the genes combining in different ways and seedlings may express different characteristics from either of the parents of the F1 generation or indeed the F1 generation itself. The extreme height of some of the seedlings which I mentioned above in my new hybrids which flowered last year would be an example of an unexpectedly variable F1 generation because one of the parents was itself a hybrid but saying that none of the parents were producing massive flowering stems 6 foot plus in height. It is possible that this unusual height might be some relict from some common ancestor these plants had with some of the modern tall monocarpic Meconopsis, hard to say with any certainty but I do think that there are possibly desirable characteristics hidden away in the DNA of some of our large flowered blue Meconopsis, getting these to express themselves is pretty much a game of trial and error because until you try, you'll never know which plants actually have the genes that you are looking for hidden away inside their DNA. It is a bit of a lucky dip!