I really hate the concept of "cultural appropriation" which is based in the belief that
a. we are all neatly divided into "races" and
b. only people of the correct "race" can do or wear certain things.
This of course goes against all of human history and is a reactionary and stupid and most importantly a completely untenable position to hold.
Most Irish people don't fetishize being Irish (except for a few of my cousins) so nobody seems to realize that Halloween is a Celtic tradition.
As history.com says:
Halloween is an annual holiday, celebrated each year on October 31, that has roots in age-old European traditions. It originated with the ancient Celtic festival of Samhain, when people would light bonfires and wear costumes to ward off ghosts. In the eighth century, Pope Gregory III designated November 1 as a time to honor all saints; soon, All Saints Day incorporated some of the traditions of Samhain. The evening before was known as All Hallows Eve, and later Halloween. Over time, Halloween evolved into a day of activities like trick-or-treating and carving jack-o-lanterns. Around the world, as days grow shorter and nights get colder, people continue to usher in the season with gatherings, costumes and sweet treats.
So idiots whining that a non-Hawaiian wearing a Disney's Moana costume is cultural appropriation - yes, it really happened need to realize is that unless you have ancestors from the British Isles, if you celebrate Halloween you are guilty of cultural appropriation.