It depends which version you are using:
- up to Orbeon Forms 4.2, resources.xml does contain that message
- starting Orbeon Forms 4.3, resources.xml contains a more complex formatted string
Question
I translated the necessary files for Dutch but apparently the runner still shows the error section in English.
I looked at both the runner and fb resource.xml but couldn't find the string 'Your form contains the following errors'.
I also have this entries in the properties-local.xml
<property as="xs:string" name="oxf.fr.available-languages.orbeon.builder" value="nl en"/>
<property as="xs:string" name="oxf.fr.default-language.orbeon.builder" value="nl"/>
<property as="xs:string" name="oxf.fr.default-language.orbeon.*" value="nl"/>
<property as="xs:string" name="oxf.fr.default-language.*.*" value="nl"/>
Solution
It depends which version you are using: