How come it "crashes" like, you aren't able to use it properly? if you're using homebrew loader, and the problem you mentioned before was caused through JKSV, then my only recommendation would be to set up a CFW and install a SVDT (the cia version) on it, but before that, did you make sure that the folders and the instructions given on the github were the correct ones? (folder placement on 3ds and such)
Yeah, the steps are like this (taken from the Pokemon Sumo save sharing thread)
1. Start SaveDataFiler and look for your actual game ID
2. Press Y to export your current savefile to the SD Card
3. Plugin your SD Card into the computer, go to the filer folder and look for the title ID to find the "main" file
4. Replace the old "main" file with the new one and reinsert your SD Card into the 3DS
5. Start SaveDataFiler and press R+X to delete your Secure Value
6. Last step, just press A to import your new savegame
That should work flawlessly