Rather than campaign_country in campaign.signup.transactional.md, it should be campaign_language.
/* Required. A country of campaign user subscribed to. Example: "US". */
campaign_country: String,
Long term, do not assume a one to one relationship of a country having a specific / one language. Example Canada: English and French. It's possible that a campaign from a country could be in more than one language or in a language that's not the default for the country.
Rather than
campaign_countryincampaign.signup.transactional.md, it should becampaign_language.Long term, do not assume a one to one relationship of a country having a specific / one language. Example Canada: English and French. It's possible that a campaign from a country could be in more than one language or in a language that's not the default for the country.