Inconsistent Part 3 `sortBy` definitions

The requirement says:
https://github.com/opengeospatial/ogcapi-processes/blob/b5105df0384254e02dd3d77f2ce24d32fc6f2506/extensions/workflows/requirements/input-fields-modifiers/REQ_input-fields-modifiers_sorting.adoc?plain=1#L6-L8

However, the schema shows:
https://github.com/opengeospatial/ogcapi-processes/blob/b5105df0384254e02dd3d77f2ce24d32fc6f2506/openapi/schemas/processes-workflows/fieldsModifiers.yaml#L13-L16

What is expected?

{ "sortBy": "a,-b,+c" }

or

{ "sortBy": ["a", "-b", "+c"] }

or both?

The string part should reuse the ordering pattern:
https://github.com/opengeospatial/ogcapi-features/blob/0c508be34aaca0d9cf5e05722276a0ee10585d61/extensions/sorting/standard/openapi/parameters/sortby.yaml#L12-L17

Also, the second part of the requirement mentions CQL2 as sorting expression.
CQL2 should allow the JSON variant as well?
Should the schema use https://github.com/opengeospatial/ogcapi-features/blob/master/cql2/standard/schema/cql2.json instead?

Furthermore, given this different sorting language, should a sortBy-lang parameter be considered?

Compare the sorting requirement in extensions/workflows/requirements/input-fields-modifiers/REQ_input-fields-modifiers_sorting.adoc with openapi/schemas/processes-workflows/fieldsModifiers.yaml. Review the referenced OGC API Features ordering pattern and CQL2 schema, then resolve which representations and language parameter are supported. Done means the requirement and schema consistently document the agreed behavior.