They literally say "$10,000" which is US DOLLARS, the IRS is not interested in the value in foreign currency, just what the value of that foreign currency is in US DOLLARS. So you would need to report any value worth over $10,000 US DOLLARS. So you'd have to calculate
The IRS is only interested if it is the value of any amount that exceeds the value of $10,000 US DOLLARS regardless if the foreign currency calculates less when converted from US DOLLARS.
Example: you have €9500.00 euro in an Italian bank, but the value of that in US dollars is $10,324.00 then YES you'd need to file FBAR because the value is over $10,000.00
Example: you have CHF 9,800.00 swiss francs in a Swiss bank, but the value of those francs in US dollars is $10,009.00 then YES you need to file FBAR because the value of what you have in the foreign bank is in fact over $10,000.00 US DOLLARS.
You would use the IRS conversion table for the year you are filing. Here--> scroll 1/4 way down on page:
https://www.irs.gov/individuals/international-taxpayers/yearly-average-currency-exchange-rates
