Using AWS OpenSearch Service with QuickSight

Question

I have a cluster in AWS OpsenService runnin ElasticSearch 7. I have created a connection to Quicksight from which I can see the indexes, so all good so far. However, I'm getting this:

I get it, QS does not support the type TEXT. However as per ES:

https://www.elastic.co/guide/en/elasticsearch/reference/current/mapping-types.html

None of the string types are supported by QS. So I tried to do cast operations via CDK (which is how I am deploying the daata set anyways):

logicalTableMap: {
    testQuery: {
        alias: 'alias',
        source: {
            physicalTableId: 'testQuery',
        },
        dataTransforms: [
            {
                castColumnTypeOperation: {
                    columnName: 'hw_id',
                    newColumnType: 'STRING',
                },
            },
            {
                castColumnTypeOperation: {
                    columnName: 'min_value',
                    newColumnType: 'DECIMAL',
                },
            },
        ],
    },
},

Which yielded exactly the same problem. the physicalTableMap is also defining the data types as I want them.

Given that none of the string data types from ES seems to be compatible with QS, what is the conclusion? That QS can't be used with OS and ES if there is a column you need with a string? How would I fix this? Has anyone tried this?

My guess is that this is probably not the only use case for this when it comes to data types, so can CDK somehow get around this?