Potentially dangerous construction mistake, rear lower wishbone 3200

I think it is not as important which is the correct reason for the failure, the fact that this discussion has raised some issues and most importantly warned us all that this can break, is however important, and I am at least thankful for this discussion.

I think we have the following we all agree on
long thread in the ball joint but make sure it does not bottom out and do not overtighten
Check you do not have too much thread sticking out the other end as a basic precaution

I certainly plan to check this ASAP