Is there anything in the logs? I have never used Loki, so not sure what could be going wrong. Are you able to add other sources or just loki is the problem?

Right, /app/data/custom.ini is where the users customizations go. What db were you using in your existing installation? The cloudron package uses postgres. To get the DB connection credentials, you can go to the Terminal of the app and do env | grep CLOUDRON_POSTGRES. You can also click the postgres button on the top and it will paste the CLI needed to access postgres.