The default human language doesn't appear to be set in any of the Gradebook document contexts.
This is critical especially for international students who use screen-reading software. Their O/S, browser, etc. may default to a different language and the adaptive technology will mispronounce all of the words (for instance, trying to read english text as if it were spanish, french, etc.). This would be a great source of user annoyance which is especially unwelcome while taking an assessment.
Most Sakai tools declare the default human language in the <html> tag. For example, the portal does like so:
<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
This issue is a failure to meet WCAG 2.0 SC 3.1.1 Language of Page: The default human language of each Web page can be programmatically determined. (Level A)
WCAG 2.0 SC 3.1.1 is described here: http://www.w3.org/TR/UNDERSTANDING-WCAG20/meaning-doc-lang-id.html
Resource: Internationalization Best Practices: Specifying Language in XHTML & HTML Content - http://www.w3.org/TR/i18n-html-tech-lang/
The default human language should not be hard coded, but instead match a users chosen language preference.