On the station thing... each 合 up a mountain trail is 10% of the way up (I believe it’s by altitude starting from the base?). So 3合目 and 7合目 are really approximations for “1/3 of the way up” and “2/3 of the way up” if you wanted to be boring.
I would conjecture (i.e., when I was a younger man I assumed
) that the choice of the term “station” could come from the practice of making specific stops on religious pilgrimages, being that Mt. Ordeals is something like a spiritual experience in the context of the game. In hindsight, this is almost certainly an eisegesis of mine that just seems to work for me
At any rate, the etymology of the term seems uncertain