Hi there @TianaS,
Thanks for sharing your question with us! Happy to share some insight here!
You can definitely add the currency code associated with the account to your API call. The reason why it isn’t natively there is because currency needs to be set up a separate property in the event and would need to use a string.
It should be noted that traditionally Klaviyo was built to work on a 1:1 level with ecommerce stores and created to separate/manage data and keep reporting/analytics as concise as possible. Therefore, if you have stores in multiple countries, we always recommend you create a Klaviyo store per instance. With that being said, you are not able to send ISO code but rather the currency symbol instead.
To gain more insight, I’d recommend checking out these similar Community threads of users who asked similar questions!
Hope this helps!
-Taylor