this applies to phantom hourglass but might work in principle in spirit tracks if you find the correct address if the JEZA signature is left intact i have not looked at the spirit tracks save file
you can graft the 0x80*2 bytes profile sections from another save where you have the name you want
just be sure to graft from the same slot you want to change. if you graft 0x100 bytes from slot one to slot two the entire save load routine will nearly crash and just say creating new file
if you use the right slot it will complain something is broken and will restore your save with the new name essentially rewriting the check sum with the new profile name. voila!
a diff now reveal that it fixed something at 0007e900 which is before the graft but i have not investigated further if this is the sum for the profile block
----
a new slot one profile has the battle name at 3ec40 with lots of blank around it and then a second one at 3f140 that are conveniently aligned in a full 16 byte block
changing it will reveal a 2 byte sum in the 3ecf0 and 3f1f0 blocks
later near the signature JEZA 4a455a41 are the smaller profile blocks also check summed
this sum can not be changed in game and i have not cracked it so i have to live with my in game name kuk or graft it from another save
fifa might be a reference for cracking the sum
https://github.com/CTurt/DARA/blob/master/CRCFix/source/main.c#L113-L122
https://gbatemp.net/threads/nds-checksums.475572/
if you need to change slot two change 0x3f424 to 0x7e924 in BOTH locations otherwise it will fail
```
strings -tx -n1 z.0
xxd -p zelda.dsv>zelda.hex
xxd -p -r zelda.hex>zelda.dsv
diff <(xxd zelda.0) <(xxd zelda.dsv)
dd if=z.1 bs=1 skip=$((0x3f424)) count=$((0x100)) of=graft.bin
cp z.0 z.2
dd if=graft.bin of=z.2 bs=1 seek=$((0x3f424)) conv=notrunc