The businesses that advertise in English in a non-English market are, almost by definition, the ones already competing for international attention. They are also the ones already receiving your competitors' emails.
The long tail is in the local language
A German plumber describes themselves as a Klempner or Installateur. A French one is a plombier. A Dutch guest house is a pension or logies. Search in English and you simply do not see them.
Why this is not just translation
A literal dictionary translation often misses the term the trade actually uses about itself. The useful expansion is the one a native speaker would type, which is frequently not the textbook word.
Combine it with geography
Local-language keywords multiplied by city and suburb level targeting is where the volume is. One country, one trade, expanded properly, is usually thousands of businesses rather than the few hundred that rank nationally in English.