Complex Derived Column Pattern with Cache Sink Lookup

Question

I'm not sure if this is a bug or a limitation but I have a some what complex Derived Column transform using a Column Pattern and Cache Sink to map/set the values of multiple columns.

Basically, for each column found using a cache sink lookup I need to match the current columns value to an array of complex types from the cached sink and return the code property.

Source

id	title	handle-time	return-window
1	Shirt	1 to 2 days	7 days
2	Pants	3 to 5 days	14 days

Desired Output

id	title	handle-time	return-window
1	Shirt	1-2d	7d
2	Pants	3-5d	14d

Cached Sink

[
    {
        "code": "handling-time",
        "values": [
            {
                "code": "1-2d",
                "label": "1 to 2 days"
            },
            {
                "code": "2-3d",
                "label": "2 to 3 days"
            },
            {
                "code": "3-5d",
                "label": "3 to 5 days"
            },
            {
                "code": "5-7d",
                "label": "5 to 7 days"
            }
        ]
    },
        {
        "code": "return-window",
        "values": [
            {
                "code": "7d",
                "label": "7 Days"
            },
            {
                "code": "14d",
                "label": "14 Days"
            }
        ]
    }
]

Everything is working as expected until I try and use the following snippet in the "Value expression" of the Column Pattern.

find(ValueCodes#lookup($0).values, #item.label === toString($$)).code

When I replace $$ with a hard-coded value of '1 to 2 days' the correct code value '1-2d' is returned and the column value is updated as expected.

If simply set the "Value Expression" to $$ the value '1 to 2 days' is returned as expected.

It appears that with in the find function $$ does not resolve.

Any thoughts or suggestion would be greatly appreciated.

Thank you!