test.cs

textControl1.Load("template.tx", TXTextControl.StreamType.InternalUnicodeFormat);

CellFilterInstructions cellFilterInstructions = new CellFilterInstructions() {
    CompareValue = 10,
    Operator = CellFilterInstructions.RelationalOperator.GreaterThan,
    TrueColor = Color.Green,
    FalseColor = Color.Red
};

textControl1.Tables[1].Cells[2,2].Name =
    JsonConvert.SerializeObject(cellFilterInstructions);

MailMerge mailMerge = new MailMerge();
mailMerge.TextComponent = textControl1;
mailMerge.FieldMerged += MailMerge_FieldMerged;

string jsonData = File.ReadAllText("data.json");
mailMerge.MergeJsonData(jsonData);