As for "Klahowya/ klahowyum", an all-purpose salutation can easily be both "hello' and "goodbye", as well as "live well" and many other things. When I was a Peace Corps Volunteer in Colombia I was often saluted in the street with "Goodbye, mister! How are you?" "Adios" was used to mean both "hello' and "goodbye", but the high school English text allowed only "goodbye". My recollection of Chinook jargon from Portland, OR, 50 years ago is that "klahowya" was like that: "salutations" or "good to see you" or "honor and respect to you", either at meeting or at parting.