I've been reading up on localisation SEO lately - as far as I understand, Google only uses "server IP is located in X country" as an indicator of where a site might be localised for, if it can't get any better information.
For example, if you're using a ccTLD for the domain, or if it's a generic-TLD and you declare a country in Google Webmaster Tools, that will be a much stronger weighting.
Thank you. The actual web app is hosted on Linode in Frankfurt (using LetsEncrypt for https) so maybe I should host the marketing page there as well if that's true.
They're not as easy to get away from as you think.