Hi Dustin,
We are working a feature exactly like this but it won't be ready til ~Q2 of next year.
However I do have a workaround.
1) Create a inbound script or modify your existing one.
2) Add an input string variable for the language. Display it somewhere on the page of the script.
3) Publish the script.
4) In your flow, add a Set Screen Pop Action before the Transfer to ACD action. Select the script you created, and set the value of the script's input variable to the language the caller is using. FYI the set screen pop action doesn't have to be immediately prior to the transfer to acd action, it can be set at any point in the flow as long as the caller gets to it before the transfer to acd action.
5) Publish the flow.
Now when agent receives the call, the script will appear to them and they will see a note saying "English" or "Spanish".
https://help.mypurecloud.com/articles/about-scripting/
https://help.mypurecloud.com/articles/set-screen-pop-data-action/