Importing internal activity

We are decommissioning a salesforce/marketing cloud environment and we would like to import internal activities into eloqua.

Have you got any suggestion?

We are thinking to import saleforce internal activities into eloqua external activities, but we would prefer to import them into eloqua internal activities in order to see those imported activites in the same way as the natives ones. In particular way it would be useful in standard reports.

We tried to use Bulk activities APIs and we imported external activities, but we were not able to import internal activities.

E.g. Tring to import a form submission with the attributes below