I've mixed kunekune with a few breeds - Berkshire, Large Black, OSB, tamworths, but haven't had mangalitzas.
If they're introduced as youngsters (when the kk are bigger than the mangalitzas) the pecking order should get straightened out quite quickly. Always give them plenty of space and two arcs/sleeping areas, expect a few tussles for a few days but it should settle.
What's the feed regime for mangalitzas, compared to kk? The biggest headache I had was keeping the kk out of the larger meals served to the other breeds, but if you can get a small holding pen within the field you can shut one breed in to make feeding different amounts easier (and it's handy for loading/handling too)
HTH Karen