Hi @ramiren ,
I would use a multi-checkbox property to track the language of their form submissions, so you have insight into all of the languages they use to communicate with you.
You might also consider a checkbox property for “multi-lingual” that is set with a workflow when you have form submisisons in multiple languages. This would allow for easier segmentation and reporting on specifically multi-lingual contacts.
From there, perhaps you can use the predominant language of their country of origin as a “tie-breaker.” For example, someone in the USA might speak English and Spanish, but the dominant language in the country is English. Assuming you have submissions in both, you can track that with your multi-checkbox, while putting them mainly in an English speaking segment.
If you are not capturing the country in the form submission, you could use IP Country as a surrogate for that.