If you somehow find an unprovable theorem (quite rare), you can always try with a different set of axioms. Mathematics are not about proving absolute truths of the universe but rather of pushing reasoning over a set of axioms the furthest possible.
Also as a nitpick, analytic systems that don't contain arithmetic can be complete and proven coherent.
As for the real world, facts that can neither be proven true nor false (existence of an immaterial soul for example), I think should be left at that. It is useless speculating about things we can't ever know of. I leave that to religion/spirituality.