If you are going to present the caller with options, you can use the Set step to store the selection to a variable. As long as you have the same WAV file name in each lanaguage directory (en_US, es_US, etc), you can build the expression like this within your Play Prompt or Menu steps:
("P[" + callerLanguage + "\example.wav]")
...or something similar to that. I'm going from memory and didn't open the CRS editor to try it.
The callerLanguage variable should hold the appropriate language folder such as en_US where your WAV prompt is stored.