How to use exchange rate from Currency Api in a field?
Here is a much leaner version of your setup:

In order to get your node to always display the current converted usd_value to EUROs, you will need only one computed field (no markup field required). 
You just will need to place the following in the "Display Code (PHP)" textarea:

$conversion_factor = CurrencyYahooFinanceCurrencyExchanger::load('USD','EUR');
$node_usd_value = $entity-&gt;field_usd_value[LANGUAGE_NONE][0]['value'];
$euro_value_live = $conversion_factor * $node_usd_value;
$display_output = number_format($euro_value_live,2);


That should be all, just tried it and I am getting the following to display. My computed field is called "EUR Value (Live)":



Hope this does the trick for you!