You wanted to make a point that time does not depend on physical location, while you chose an example that proves otherwise.
There is no absolute time in spacetime, so your calendar invite from an alien friend would include not only the coordinates on Jupiter but also a time value relative to something. Possibly Earth. Maybe even UTC, as observed on Earth.
Please don't bring relativity into this except as a fun side note. It doesn't make a meaningful difference for actual objects in space, because they all share basically the same reference frame.
There is no absolute time in spacetime, so your calendar invite from an alien friend would include not only the coordinates on Jupiter but also a time value relative to something. Possibly Earth. Maybe even UTC, as observed on Earth.