If we would like to check transactions in crypto currencies, is it possible to send transaction_amount as xx.xxxxxxxxx (lots of digits after .)? And transaction_currency like BTC, etc.?

The `transaction_amount` is limited to 15 decimals, which should be fine for BTC for instance. As of now, we fetch currency exchange rates in order to calculate the sum of the transaction amount regardless of currency. We do not support BTC, so our system won't do the exchange in these cases.