You would essentially forgo the languages and instead replace them with countries or regions, with the suggested workaround.
For custom work I am not familiar with an actual solution, however, WPML has an API so possibly with the right developer and experience they might be able to do this, but I cannot guarantee this.
All developers listed here are experienced with our product, and they should be able to know if this would be within their capabilities. https://wpml.org/contractors/
In my opinion this solution is something WPML should include in their plugin. A lot of users will have the English language in combination with multiple currencies for their English speaking visitors. They all want that their visitors see their own currencies in search results. I know you guys can't influence Google but you can influence the information that Google receives / indexes.
For now I understand that this is not included and I asked contractors for a quote on the forum.
For the rest I want to say that I'm very satisfied with WPML and with your help. Thanks so much!
