Whew, so this is another thing that's turning out to be way more complicated than I originally expected.

So whereas tile layout data for the us version is pretty straightforward - all tiles arranged in order (except only 28 rows are used - the last 0x100 bytes are seemingly worthless) - the Japanese layout is... Not so simple.
The layout data begins (as far as I can tell) at 46800. There's 0x180 bytes representing the top layer of "FINAL FANTASY IV" followed by 0x180 bytes for the bottom layer. Each of these layouts fills only the vertical space occupied by the FINAL FANTASY letters. Somehow the game knows not to put anything in the top 8 or so rows.
After the layout data for FINAL FANTASY IV, there's a few bytes that are doing... Something... Then there's layout data for one layer of the crystal. It's the layer that shows up second (not the image of the crystal that appears before anything else). I don't know if it's the top or bottom layer because they're not off-set like the letters are. the crystal layout data only arranges tiles within the vertical and horizontal space occupied by the crystal. Again, somehow the game simply knows not to put anything in the empty (black) space. I don't know where to find the layout data for the other layer of the crystal, but I've kinda run out of steam for the day, so I stopped looking.
I also documented just about every routine FFIVJ runs up through the title screen. Unfortunately, there's
a lot more going on there than in FF2US, but creating something that is similar enough seems within reach.
The biggest roadblock I'm facing here is that I have no idea how the SNES handles graphics in layers.
Using the information I've gathered thus far, I could probably put together a fairly reasonable facsimile of the Japanese title screen in the US version, including (probably, but I'd have to write my own routine, I think) the flashing effect... But I don't think I know enough about SNES graphics processing to recreate multiple layers.
Not that I'm not willing to learn, but I don't really know where to begin.
Anyone have any insight into this?