There have been a few posts related the same issue but I have not seen a solution: when using SQLite in a sandboxed app the database's journal file cannot be opened. What kind of sqlite database naming, entitlements, info-plist settings etc. are required to let SQLite open a journal file?
Have you read the documentation on SQLite temporary files at https://www.sqlite.org/tempfiles.html? It seems self contradictory. Section 2.1 says that a rollback journal is in the same directory as the database file, while section 5 says that temporary files are elsewhere. Are you getting an error message telling you the path of the file that can't be opened?