Ok, I tried what you suggested, and I got the same offset I got when I was looking at LZ decompression: 0xD77D68. But the table that has that pointer would only have 10 backgrounds, if we go by the format in your tutorial. Maybe I'm just looking at the wrong images?
Do you mind helping me out with something?
I'm trying to expand the battle background table for Emerald, and I can't find the battle background table, for some reason. I did what you said to do in your post about using the logging feature in vba-m, but I can't find it.
Just to make sure I wasn't doing anything wrong, I tried doing the exact same thing with Firered, and i successfully found the offset you listed in the tutorial (0x24844C for the grass battle background), so I'm not sure what's going wrong for Emerald.