you may be able to decrypt it in vita shell. I've never personally done this. what I did to transfer saves is decrypt the save with save manager under the original account, then reencrypt it under a different account. I think you may need to erase the patch afterwards too, because saves, at least were, redirected to the data folder. deleting the patch in vita shell will force them to be read from the default location ux0:user/00/savedata/title id. some saves are weird like the tales of hearts one. I think it uses the European title id, yet the American id is present. I think I played around with it for a bit, and changing the American one yielded failure. changing the European saves worked. you may need to create a save first with the game to overwrite it, because I think saves need to be indexed. this is also how it works on the ps4.