Those memory addresses (ex: 7F0001, bit 01) are only flags for whether you've opened a chest. In other words, the Off/On setting so chests can only be opened once.
The actual data for coordinates and such is loaded directly from ROM at around the $350000 range, IIRC.
It will need to be changed manually in a hex editor. Let me know what room #, and what the chest(s) originally contain and I'll .IPS it.