You can download the JSON file of fields configuration for MLCS from the server or data center and import it into MLCS Cloud.
Export json tree from MLCS Server / DC
Go to Settings → Issues
Go to Custom fields on left side and edit MLCS Custom field type, click on 3 dots ... → configure
Go to edit options of your custom field type
Export json tree file on right side (required plugin version 6.21.0 or newer)
Import json tree from MLCS Cloud
Go to Settings → Issues → custom fields → mlcs → ... → context and default value → edit custom field config
Go to MLCS Cloud on left side and open tab "Import / Export"
Choose json file from MLCS Server / DC and import it.