Hi,
as of now we have automatic tests to ensure conformance with WCAG 1.1 (see https://dev.xwiki.org/xwiki/bin/view/Community/WCAGTesting), we started to perform changes to adapt to WCAG 2.0 but it’s still a work in progress (https://design.xwiki.org/xwiki/bin/view/Improvements/Accessibility).
We got very recently a new report about some problems to fix for passing WCAG 2.0 AA, so it’s probably something we will work on for next cycle.