Ok I started looking into analytics, but ended up just relying on a save search.
The user wanted a report of the bank balances in their currency at a point in time without having to go to the bank registers. I created a save search that either displays the {amount} or {fxamount} based on account internal id. Luckily there were only 4 accounts that fell into that category, but would have been nicer to have the field available.
Please let me know if there was a better way to handle this kind of report.