Why doesn't "koverto" take the accusative in this sentence? Thinking about some of the examples on Lernu: "La muso saltas sur la elefanto," is a lot different than "la muso saltas sur la elefanton," the difference being in whether the mouse is on the elephant and is jumping or if the mouse is jumping onto the elephant from somewhere else. Same sort of thing: was he inside the envelope when he hid the money, or did he hide the money in(to) the envelope? Maybe I'm just over-analyzing this sentence, but it looks like it should read as, "Li kasxis la monon en la koverton."
In the song "La Erinaco", grandpa finds a hedgehog and hides it underto a cloth.
Nia avo foje trovis erinacon en ĝarden'
Kaj li kaŝis ĝin sub tukon sur la benko ĉe kamen'.
I feel like I dug into this a bit the last time someone asked and failed to find very many other examples of kaŝi being used to describe motion.
Apparently this has come up before.