Switch - Help with Save and MetaSave

[theraos]

Hi, i would like to know if you can help me. Happens that i, stupidily, upgraded the consoles´s firmware, and in the despair that atmosphere didn´t boot, i formatted the sd card. Due to not being able to install other apps like jksv or checkpoint in order to backup the save data i simply copied the save and metasave folders in the user folder of the emmc. Can i assign that save files to new accounts, and if so, how can i do it?. Thanks in advance!