Salesforce multi-select picklist values can appear with # delimiters during Apsona merge processing. To display the values in a readable format such as “Item 1; Item 2; Item 3”, create an Apsona Single-Step Report to use as the sublist data source and add a JavaScript Calculated Field that replaces the delimiters with the desired formatting.
The merge can still be triggered directly from the Salesforce record. Add the calculated field to the sublist report and map it to the Document Merge in place of the original multi-select picklist field. Ensure the JavaScript formula references the actual multi-select picklist field being used.