Most of the limitations are on the size of the data eg the ROM data can't be more than 0x2000000 bytes in length and the screen resolution (240x160p) etc
It confirms my hypothesis; you see it says Goddess Icon in memory because that's the "current item" in whatever reserved byte the game uses. The whole store system including the graphics and options and displaying items is linked to the 0x1A byte being used in the text so check the actual ROM text for a stray 0x1A probably from an overflow or something
open the memory viewer, type in or paste in the address and click Go when the conversation is happening like in the photo
you can alternatively look at the actual ROM data in a hex editor by searching for the ascii text