The ordering of the form fields is not reflected in the API. What should I do?

By default, the cols response outputs form fields as objects.
In the Endpoint settings dialog, under "Advanced settings", set "cols_type" to [array] to output the objects in a specified order.

"cols_type" as array

Setting "cols_type" to [array] automatically outputs the cols response in an ordered array.

Example output:

{
    "cols": [
        {"key": "ext_1", ...},
        {"key": "email", ...},
        {"key": "ext_2", ...},
        {"key": "name", ...},
        ...
    ]
}

"cols_type" as object

If you leave "cols_type" blank or set it to [object], the cols response will output objects in no particular order.

Example output:

{
    "cols": {
        "ext_1": {...},
        "ext_2": {...},
        "email": {...},
        "name": {...},
        ...
    }
}

However, the sorted key names are outputted under ordered_keys.
You can use this to display the keys in a specified order on the front-end as follows:

{
    "cols": {
        ...
    },
    "ordered_keys": [
        "ext_1",
        "email",
        "ext_2",
        "name",
        ...
    ]
}