Testing compatibility in co-dominants is tricky. Take the white snake complex. Distinctly different looking animals from lessers to Vin Russo high lemon yellows can apparently be crossed to make a super white snake. The test is the next generation when the cross line white snake breeds to a normal. As far as I know they have always produced 50/50 splits of the two lines and no normals and no white snakes. This indicates that the two lines where likely alleles - different mutations of the same gene. It's possible they are just very near loci and a crossover could eventually happen between them but most likely given the "super" combination that they are alleles.

However, when pastel jungle and cinnamon pastel where crossed and produced the super looking pewter subsequent breedings proved they where two different genes. We now have animals like silver bullets having more than two copies of the two genes combined. This would not be possible in a situation where a single gene with multiple mutant variations was involved. You should not be able to produce a mojave + Vin Russo + lesser because there is only room for two copies of any one gene.

So IMHO the test for enchi compatibility will not be just to produce a super looking combination with pastel. Even if they are separate genes when you cross a regular pastel with an enchi pastel you would expect to get 25% normals, 25% regular pastel only, 25% enchi pastel only, and 25% both genes combined. The cumulative effect of both genes combined might look super without them being the same gene. The test if they are different versions of the same gene will then be if the super is bred to a normal and produces only 50/50 regular pastel and enchi pastel with no normals and no supers. If they are different genes, then the super could produce 25% normals and 25% supers along with the two parent types. Again, there is the possibility of linkage if they are two separate genes on the same chromosome complicating these results.

All this assumes that they aren't the same version of the same gene which may well be the case with some of the named pastel lines. In some cases, line breeding may have isolated multiple other genes that make a family resemblance like extremely bright or faded but the exact same pastel gene is seen in that line as other lines. If the enchi looks consistently different you would expect that even at that first step when you cross with another pastel line you could continue to pick out the two different lines in the offspring indicating that there may well be a different version of the pastel gene involved.