Json way

void Main() {
    var wb = LoadWorkbook(@"D:\Downloads\EU.xlsx");
    //  wb.DocumentSettings.Calculation.Mode = DevExpress.Spreadsheet.CalculationMode.Manual;
    //  wb.Worksheets["Output"].Range["A49:E70"].ExistingCells.Select(x => $"{Column.FromNumber(x.ColumnIndex + 1)}{x.RowIndex + 1} {x.Value.TextValue}".Dump()).ToArray();
    var doc = ProcessBlock(wb.Worksheets["Output"], 50, 1);
    doc.ToString().Dump();

    doc.ToObject<Premium>().Dump();
}

JObject ProcessBlock(Worksheet worksheet, int topRow, int leftColumn) {
    Newtonsoft.Json.Linq.JObject root = new Newtonsoft.Json.Linq.JObject();

    int row = topRow;
    while (true) {
        JToken content = null;
        string elementName = "";
        int height = 0;
        var value = worksheet[row, leftColumn].Value;

        if (value.IsEmpty) {
            break;
        } else {
            elementName = value.TextValue.RemoveWhiteSpaces();
            if (elementName.EndsWith(CollectionSuffix)) {
                (content, height) = ParseToCollection(worksheet, row, leftColumn);
            } else if (elementName.EndsWith(TableSuffix)) {
                (content, height) = ParseToTable(worksheet, row, leftColumn);
            } else {
                content = ParseToSingleElement(worksheet, row, leftColumn);
                height = 1;
            }
        }
        root[elementName] = content;
        row += height + 1; // +1 for the empty row under the collection
    }
    return root;
}

JToken ParseToSingleElement(Worksheet worksheet, int row, int leftColumn) {
    return worksheet[row, leftColumn + 1].Value.ToString();

}

(JObject table, int tableHeight) ParseToTable(Worksheet worksheet, int topRow, int leftColumn) {
    var tableBodyRow = topRow + 1;

    //get labels from the area under table header
    var labelsColumn = worksheet.Columns[leftColumn];
    List<string> labels = GetColumnValuesUntilEmpty(labelsColumn, tableBodyRow);

    //get element properties from the column to the right of lables
    var elementColumn = worksheet.Columns[leftColumn + 1];
    var element = GetElement(elementColumn, tableBodyRow, labels);
    var totalTableHeight = labels.Count + 1; // +1 for the header of the table

    return (element, totalTableHeight);
}

(JArray collection, int collectionHeight) ParseToCollection(Worksheet worksheet, int topRow, int leftColumn) {
    JArray array = new JArray();
    // get collection elements from the area under the header of the collection
    var (elements, elementsHeight) = GetCollectionElements(worksheet, topRow + 1, leftColumn);

    elements.ForEach(x => array.Add(x));
    var totalCollectionHeight = elementsHeight + 1; // +1 for the header of the collection

    return (array, totalCollectionHeight);
}

(List<JToken>, int elementsHeight) GetCollectionElements(Worksheet worksheet, int topRow, int leftColumn) {
    List<JToken> elements = new List<JToken>();

    var labelsColumn = worksheet.Columns[leftColumn];
    List<string> labels = GetColumnValuesUntilEmpty(labelsColumn, topRow);

    // get collection elements from the area to the right of labels column
    for (int columnIndex = leftColumn + 1; ; columnIndex++) {
        var elementColumn = worksheet.Columns[columnIndex];
        var element = GetElement(elementColumn, topRow, labels);
        if (element != null) {
            elements.Add(element);
        } else {
            //right edge of the collection reached
            break;
        }
    }
    return (elements, labels.Count);
}

JObject GetElement(DevExpress.Spreadsheet.Column elementColumn, int topRow, List<string> labels) {
    JObject element = null;
    var properties = GetColumnValuesUntilEmpty(elementColumn, topRow);
    for (int i = 0; i < properties.Count; i++) {
        element = element ?? new JObject();
        element[labels[i]] = properties[i];
    }
    return element;
}

List<string> GetColumnValuesUntilEmpty(DevExpress.Spreadsheet.Column column, int topRow) {
    List<string> labels = new List<string>();

    for (int row = topRow; ; row++) {
        var value = column[row].Value;
        if (value.IsEmpty) {
            //bottom reached
            break;
        } else {
            labels.Add(value.ToString());
        }
    }
    return labels;
}