Although MLCS is not directly supported in EazyBI, data can be imported using the advanced options provided.
You can follow the article made by the EazyBI team that explains how to import a Multi-Level Cascading Select field as an Account-specific calculated field
or a Global calculated field: https://docs.eazybi.com/eazybi/data-import/data-from-jira/javascript-calculated-custom-fields/calculated-field-examples/multi-level-cascading-field.