Missing translations after importing the UI from the XAR

Steps to reproduce:

1. Download the 5.2M1 WAR from here, the 5.2M1 XAR from here and the HyperSQL file from here
2. Extract the WAR in its own folder
3. Rename the xwiki-manager-web-5.2-milestone-1 folder to xwiki and move it inside your webapps folder of Jetty
4. Copy the hsqldb-2.3.0.jar file inside your xwiki/WEB-INF/lib folder
5. Edit the xwiki\WEB-INF\xwiki.cfg file to enable the superadmin user (delete "#" from this line: "# xwiki.superadminpassword=system")
6. Start Jetty and login using these credentials: superadmin/system
7. Hover over Wiki -> Administer Wiki and import the XAR
8. Go to the Wiki homepage

You will see there are some missing translations. If you restart the server everything works fine.
This bug doesn't reproduce if instead of importing the UI XAR you install the UI using the Distribution Wizard.