Thank so much liomajor, you are amazing. It took me a few hours, but now that I finally understand how to do it I can comfortably do so later on. The hardest part was finding a usable savedatafiler.cia and understanding what the function of the 000400000FF40A00.sav was. I was able to convert my EU MH4U.3dz save to a US MH4U.3dz.
For anyone trying to convert a MH4U save to one of another type.
SaveDataFiler: Find a SaveDataFiler.csu and drop it in the folder from the download in this post: "
https://gbatemp.net/threads/how-to-put-savedatafiler-on-homescreen.373756/page-2#post-5150788" then run the .bat and take the .cia that is created and install it with BigBlueMenu (check
here if you don't have that yet) cia's are installed from the SD card of your 3ds.
Once you have SaveDataFiler.cia installed you can begin the process of exporting both the US and EU save data as explained in this post: "
https://gbatemp.net/threads/tutoria...v-to-eshop-3ds-3dz-with-savedatafiler.380246/"
That post needs to be combined with this one in order to achieve the intended effect:
1. Export your EUR save (00001261)
2. Create a save inside MH4U USA
3. Export your dummy USA save (TitleID-LOW 0000XXXX)
4. Copy the content inside SDCARD:\filer\UserSaveData\<DATE-TIME>\00001261 to your USA folder and overwrite 'system' & 'user1'
5. Import your save for CIA
MH4U EU .3dz save to MH4U US .3dz save
-You need both the US and EU versions of the game to do this
-This is assuming you already have an EU 0004000000126100.sav and want to use it for US
-You will be turning your 3DS off and on often
-BACK UP BOTH SAVES TO YOUR COMPUTER AND REMEMBER WHICH IS WHICH
-0004000000126300.sav is US and 0004000000126100.sav is EU
1. Create a dummy save in the US version of MH4U and then rename 0004000000126300.sav that is on your SD card to 000400000FF40A00, this will allow you to export the UserSaveData by making the CTR unbroken (it would be broken if 000400000FF40A00 was not present)
2. Mount MH4U US with the 000400000FF40A00 dummy save present and then open SaveDataFiler and export the save, which will route to SDCARD:\filer\UserSaveData\<DATE-TIME>\00001263
3. Rename your MH4U EU save with all your progress on it from 0004000000126100 to 000400000FF40A00, again allowing SaveDataFiler to export the UserSaveData in the exact same manner.
4. Mount MH4U EU with the 000400000FF40A00 save present and then open SaveDataFiler and export the save, which will route to SDCARD:\filer\UserSaveData\<DATE-TIME>\00001261
5. Now Copy the content inside SDCARD:\filer\UserSaveData\<DATE-TIME>\00001261 to SDCARD:\filer\UserSaveData\<DATE-TIME>\00001263 and overwrite 'system' & 'user1'
6. Now go back to SaveDataFiler and import the modified 00001263 save from the far right tab.
7. Turn off you 3DS and open your SD card to find the newly
created 000400000FF40A00 save which will be your modified MH4U US .sav file. Rename 000400000FF40A00 to 0004000000126300, replace the dummy 0004000000126300 file if it's still there.
8. You should be able to load MH4U US without it reformatting your save data and play with all your EU game progress and probably download the starter pack.