Multi-Currency Exchange Rate

If you plan to show a manual journal entry the journal entry should look like the following:

-1000 EUR Bank Account
+1000 EUR EUR/HUF Trading Account
+278173 HUF Cash
-278173 HUF EUR/HUF Trading Account

For a manual GL entry there isn't a need to store an exchange rate. The effective exchange rate is recorded with the entries into the EUF/HUF Trading Account.