Hi Gary,
As far as I can tell, the nested metadata feature should be able to support other metadata schema, as long as the schema, element, and qualifier are defined. The example given in the documentation for a non Dublin Core schema is within a child form, but it should be the same format within the parent form:
<dc-schema>oairecerif</dc-schema>
<dc-element>author</dc-element>
<dc-qualifier>affiliation</dc-qualifier>
However, I haven't tested it myself and that could be incorrect, so if anyone more familiar with the feature knows otherwise please let us know.
Either way, it would be best to determine if the error you're encountering is due to the schema or something unrelated. What was the full configuration you added to submission-forms.xml that resulted in this error? Also to confirm, the nested metadata feature did work as expected with a Dublin Core parent field?
Last, the error indicates something going wrong with "securityLevel" which is related to the
Metadata Security Configuration feature also added as part of 10.0. Not sure how, but I'd also recommend checking that documentation in case there's something going on with the interaction between those two features.
Hope that's a start. Best,
-Lia