One thing you can try is to treat the English fields as the "main" fields you will be reporting on. When the form is set to English, the English fields show up and the data will be entered in them. When the form is set to Spanish, the Spanish fields show up and the English fields are hidden. For this case, you can change the field rules to "Save data when the fields are hidden" and set a formula to =SpanishField. That way, when Spanish speakers are filling out the Spanish fields, it is also filling out the hidden English fields as well, and that data will be saved on submission. Then the reports can be built on just the English fields.