Well, I stand very corrected.
I always assumed they were in a post RotJ context since the Ewoks spoke Basic and were friendly to humans. Also, the Towani family seems to be in that "post war casual travel" mode. And didn't Quaker Oats crash there during the war??? How long do Ewoks live, anyways...?
I'm sure they can't exactly be fixed in the timeline and have it make tons of sense. It's too square a peg to fit in the canon.