I was reading the Sport Aviation archives from the 50’S. They used casein (milk) glue. It said the glue shear strength was 250 psi., as I recall. So if that casein glue was good enough then, another modern glue that exceeds 250 psi shear might also be adequate, even if not as strong as epoxy in some ways. The joints need to designed with enough glue area in any case.