Does not necessarily need to be FTL. It may be a generational ship, or potentially simply these aliens have very long lifespans, and travelling the cosmos is no

Does not necessarily need to be FTL. It may be a generational ship, or potentially simply these aliens have very long lifespans, and travelling the cosmos is not a problem for them, because they anyway measure their lifespan in millennia. I agree with you though, no reason to assume that these aliens would have definitely solved all of the engineering challenges visiting a planet might pose, especially considering our own track record shows that we are relatively good at getting stuff to its destination in the solar system, but not so great at low altitude manoeuvres or landings when we get there. (to be clear, I don’t think that we’ve been visited by aliens, just that it doesn’t seem to be impossible).