It is not "difficult" to correct mistakes, but WikiTree does suggest that changes be based on sources and involve collaboration with the profile manager. These suggestions help our one-world tree have more validity than unsourced trees found elsewhere. So, just contact the profile manager with your suggested change and provide a source. If the profile manager does not respond in a reasonable time but you provide a source, if you are a WikiTree member you can go ahead and make the change yourself.
