Does anyone know how to set up a customer invoice template in a different language? Will I be able to toggle between the different languages based upon my chosen template? Will all the fields still work the same way?

You could use a separate form, with a separate adv pdf, and set that form based on the customer or other input criteria. Within the adv pdf, you could have an if statement with the same code below in its separate langauge. But you'd have to have the criteria on the record to get it to enter that if statement

Use language on the customer and translate in your advanced pdf template with if statements based on the customer’s language.

Thanks for the responses! I just want a custom invoice but wish to manage it centrally here in the US. Really it is just an option during the print invoice process...

Only print outs could be affected.