I'm not certain why this didn't make a green saproling other than the creature type matters.

Well, it does matter and that might be a good enough reason.

I like what this name can add to world-building.

According to your notes the "Crawl" is one term that encapsulates what all races do. It might be nice to distinguish how races feel about their journey - e. g. Goblins may call it the 'Great Expedition' (being a little "out of touch" with the ground-dweller's way of experiencing things), Khatna would be too easy-going to adopt the depressing name and call it the 'Trek of the Free' etc.

I made the name during a depressing time. That's some good stuff to think about when I expand the flavor. I do want a unifying word for the experience of gradually and endlessly moving forward with imminent doom always behind you. But "life" is already in use.

That said it occurs to me that the phenomenon of the plane itself is what I describe when I say the Crawl.