It seems you may not appreciate that directions on the sphere are ALWAYS relative to a reference point. When we speak of longitude specifically, the reference point is Greenwich, England. But when you use language like "east of" or "eastern," or "west of" or "western," any reference point can be used. Typically, the reference point is the speaker's current location unless otherwise stated. Yet your initial question, and all your responses in this thread, assume that Greenwich, England is always the reference point for any question of east and west. That is not correct.

When StantonMac said "Relative to where?" above, you replied "The earth." But what you meant was relative to Greenwich, England because you were relying on a longitude measurement. You were correct above when you said "latitude and longitude don't change depending on where you are." That is because the equator and Greenwich are always understood as the reference points when speaking of latitude and longitude, respectively. However, you also said "Directions... don't change depending on where you are." It is beyond question that that is an incorrect statement. If I am in Colorado, Utah is west of me. If I am in Nevada, Utah is east of me.

You said "Semisopochnoi, Alaska is always east of Japan." However, if you were in Ireland (or any other location 180 degrees longitude apart from a location between Japan and Semisopochnoi), you wouldn't say Japan is to the east and Semisopochnoi is further to the east (as you would if Semisopochnoi were "always east of Japan." You would say Japan is to the east and Semisopochnoi is to the west.

Similarly, Semisopochnoi is west of Tanaga even though the former has an eastern longitude and the latter has a western longitude, just as Japan is west of California despite the former having an eastern longitude and the latter having a western longitude. Based on your statements in this thread, it seems you would argue that Semisopochnoi is east of Tanaga, but the only observer who would agree would be one who was starting off somewhere in the 80 or so miles between the two islands and planning to sail east all the way around the world to Semisopochnoi.