Well, after some research, I discovered that in the field scripts, variables of offset 0xF are always set with the SETBYTE command, while variables of offset 0x7 use SETWORD. Same for the commands INC & INC2, DEC & DEC2, and some more. So I'm almost sure that the 2 offsets might be inverted.
But, because the 2 offsets are pointing to the same bank, the same data, it's only the way the field script engine access it that changes. That may be why Black Chocobo works anyway, it probably access the datas on its own, it may not bother on the offsets.