Disclaimer: This worked for our use case, and as with anything on the platform, there are probably many other ways to do this. (Except OOB)

One major draw back to assessments/surveys is the inability to filter the results displayed in reference metric fields. ServiceNow simply states that "Note: Reference qualifiers are not supported." and expects the end user to do the filtering based on the the entire table returned as a result. Our requirement was to pre-filter the results in a dynamic way for each specific reference field on an assessment. We created a re-usable and dynamic process to do so using a table to hold all the metric questions references, filters, and business rules that create QUERY business rules on the reference remote table to pre-filter the results before they are returned to the assessment and displayed to the user.

To accomplish this we did the following-

Create a script include that creates/removes business rules and builds the filter query.

Name: AsmtRefUtils

Client Callable: True

var AsmtRefUtils = Class.create();
AsmtRefUtils.prototype = Object.extendsObject(AbstractAjaxProcessor, {

    buildBusRule: function(table){
        // Check input variables to identify client or server side
        if(gs.nil(table)){
            table = this.getParameter('sysparm_table');


            // Validate variables are not empty if so return error
            if(gs.nil(table))
                return "ERROR: Invalid Inputs";
        }


        // Make sure the rule doesnt already exist and activate it if nessessary
        if(this._checkBusRuleExists(table)){
            this._enableBusRule(table);
            return "SUCCESS: Business Rule Exists.";
        }

        // Create the advanced script
        var advancedScript = "(function executeRule(current, previous /*null when async*/) {\n";
        advancedScript += "   try{\n";
        advancedScript += "      var url = gs.action.getGlideURI();\n";
        advancedScript += "      if(url.includes(\'ASMTQUESTION\')){\n";
        advancedScript += "         var encodedQuery = new AsmtRefUtils().buildEncodedQuery(url);\n";
        advancedScript += "         if(encodedQuery)\n";
        advancedScript += "            current.addEncodedQuery(new AsmtRefUtils().buildEncodedQuery(url));\n";
        advancedScript += "            \n";
        advancedScript += "      }\n";
        advancedScript += "    }catch(e){}";
        advancedScript += "})(current, previous);";

        var bsRule = new GlideRecord('sys_script');
        if (!bsRule.canCreate())
            return "ERROR: You do not have permission to create business rules on table " + table + ".";

        bsRule.initialize();
        bsRule.name = 'Auto generate Assessment Ref Filter';
        bsRule.description = 'Auto generated business rule to filter Assessment reference field results.';
        bsRule.collection = table;
        bsRule.active = true;
        bsRule.advanced = true;
        bsRule.when = 'before';
        bsRule.action_query = true;
        bsRule.script = advancedScript;
        bsRule.insert();        

        return "SUCCESS: Business Rule Created.";
    },

    removeBusRule: function(table){

        // Check if other reference rules exist for the table, if none remove business rule
        var asmt_ref_rule = new GlideRecord('u_asmt_ref_filter');
        asmt_ref_rule.addQuery('u_ref_table', table);
        asmt_ref_rule.query();

        if(asmt_ref_rule.next())
            return;

        // Remove table business rule
        var bsRule = new GlideRecord('sys_script');
        bsRule.addQuery('collection', table);
        bsRule.addQuery('name', 'Auto generate Assessment Ref Filter');
        bsRule.query();
        if(bsRule.next()){
            // bsRule.deleteRecord(); Inactivate vs Delete
            bsRule.active = false;
            bsRule.update();
        }
    },

    buildEncodedQuery: function(url){
        // Parse the question sys_id from url
        var r = /ASMTQUESTION%3a([0-9a-f]{32})/;
        var asmt_question_id = r.exec(url)[1];

        // Get the question record
        var asmt_question = new GlideRecord('asmt_assessment_instance_question');
        asmt_question.addQuery('sys_id', asmt_question_id);
        asmt_question.query();
        if(asmt_question.next()){       
            // Query the Assessment Reference Filters
            var asmt_ref = new GlideRecord('u_asmt_ref_filter');
            asmt_ref.addQuery('u_asmt_metric', asmt_question.metric);
            asmt_ref.query();

            if(asmt_ref.next()){
                return asmt_ref.u_asmt_ref_filter;
            }
        }
        return;
    },

    _enableBusRule: function(table) {
        var gr = new GlideRecord('sys_script');
        gr.addQuery('collection', table);
        gr.addQuery('name', 'Auto generate Assessment Reference Filter');
        gr.addQuery('active', false);
        gr.query();
        if(gr.next()){
            gr.active = true;
            gr.update();
        }       
    },

    _checkBusRuleExists: function(table){
        var gr = new GlideRecord('sys_script');
        gr.addQuery('collection', table);
        gr.addQuery('name', 'Auto generate Assessment Reference Filter');
        gr.query();
        if(gr.next()){
            return true;
        }
        return false;
    },

    type: 'AsmtRefUtils'
});

We created a table that gave admins a dynamic way to add new filters to any assessment metric with a reference question.

Name: u_asmt_ref_filter

Adding a reference qualifier to the Assessment Metric reference field "datatype=referencecategoryISNOTEMPTYEQ"

Then create two business rules on the "u_asmt_ref_filter" table. One that creates a business rule on the referenced table and another to remove/cleanup the business rule.

Name: "Create Table Query Business Rules"

Before/Insert

Script:

(function executeRule(current, previous /*null when async*/) {

    var asmtRefUtils = new global.AsmtRefUtils();
    var result = asmtRefUtils.buildBusRule(current.u_ref_table);
    if(result.includes('ERROR')){
        gs.addErrorMessage(result);
        current.setAbortAction(true);
    }
})(current, previous);

Name: "Remove Table Query Business Rules"

Async/Delete

Script:

(function executeRule(current, previous /*null when async*/) {

    var asmtRefUtils = new global.AsmtRefUtils();
    var result = asmtRefUtils.removeBusRule(current.u_ref_table);
    if(result.includes('ERROR'))
        gs.addErrorMessage("Error removing query business rule on " + current.u_ref_table);
})(current, previous);

Then we added a new module entry in Assessments > Administration > "Reference Filters" that shows the list of records in the "u_asmt_ref_filter" table.

Now any time the table is queried, the URL is examined and if its being referenced from an assessment, the assessment question/metric is identified and the filter table queried. If there are any matches to the assessment question, the results are filtered before returned to the survey/assessment. Making for a much simpler user experience taking/completing the assessments.

Admin UI-