使用一些正则表达式，我们可以将数据转换为有效的JSON，假设数据与提供的一样。

const string data = "[[WALLET_TYPE,CURRENCY,BALANCE,UNSETTLED_INTEREST,AVAILABLE_BALANCE,LAST_CHANGE,TRADE_DETAILS],[WALLET_TYPE,CURRENCY,BALANCE,UNSETTLED_INTEREST,AVAILABLE_BALANCE,LAST_CHANGE,TRADE_DETAILS]]";

//Using Regex we can wrap all UPPERCASE_WORDS with "'s making it valid JSON
var jsonData = Regex.Replace(data, "([A-Z_]+)", "\"$&\"");
var parsedData = JsonConvert.DeserializeObject<List<List<string>>>(jsonData);

现在您有了一个有效的List of List。
下面是regex 101 https://regex101.com/r/xoc7MK/1中的相同数据/正则表达式

Edit假设每个数组中始终有7个项目：

const string data = "[[WALLET_TYPE,CURRENCY,BALANCE,UNSETTLED_INTEREST,AVAILABLE_BALANCE,LAST_CHANGE,TRADE_DETAILS],[WALLET_TYPE,CURRENCY,BALANCE,UNSETTLED_INTEREST,AVAILABLE_BALANCE,LAST_CHANGE,TRADE_DETAILS]]";

//Remove all but Letters, Numbers, Commas, Underscores and punctuations 
var dataCsv = Regex.Replace(data, "[^a-zA-Z0-9_.,]", "");
var items = dataCsv.Split(',');

List<List<string>> itemsList = new List<List<string>>();
for(int i = 0; i < items.Length; i += 7) {
    itemsList.Add(new List<string>(items.Skip(i).Take(7)));
}