I think the tool can't do the bmp->dat process because the data is manipulated for doing dat->bmp.
As far as I can see the dat is just compressed with the falcom algorithm (falcom or falcom_din):
get ZSIZE asize
xmath SIZE "ZSIZE * 10"
get NAME basename
clog NAME 0 ZSIZE SIZE
As you can see the decompressed file isn't readable so its content requires some work.
It was just a quick test I did and the size of the decompressed data matches the expected one, I didn't check if the algorithm is 100% the same used in the tool.