Tax amount not calculating on External voucher template

When the tax_amount field is left blank on an external voucher import or removed from the template, IFS leaves the Tax Amount in Acc Curr blank and users have to manually convert the currency tax to the accounting tax. In our template, we have only the currency_amount and IFS converts that amount using the currency rates to automatically show the accounting amount. Why does it not do the same for the currency_tax_amount and automatically convert it to the accounting tax amount? To convert it manually in the external file before importing, users have to go look up the currency rate that will be used by IFS to convert the currency amount to the accounting amount so the voucher won’t be out of balance, then put the amount in the file before importing. Or import it, get an error, and manually type in the amount in the accounting tax amount field.