Translations are missing for some pages on a subwiki created from template

This issue was described by lucaa in https://jira.xwiki.org/browse/XWIKI-17886?focusedCommentId=107057&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-107057

STEPS TO REPRODUCE

1. Create a subwiki using the Standard Flavor by setting it as template
2. Create a new subwiki using the template
3. On the subwiki, go to Main Page, Sandbox and Administration pages

EXPECTED RESULTS

The subwiki created has the all pages displayed properly in the language of the template.

ACTUAL RESULTS

As Anca mentioned, the language of the main page of the created subwiki was displayed properly but in administration there were some translations missing and the Sandbox page was in brazilian portuguese.

The issue was reproduced both when the template was single language (french) but also when the template was multilanguage - with french as default.

For more details see https://jira.xwiki.org/browse/XWIKI-17886?focusedCommentId=107057&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-107057

Also when the subwiki creation process was being stuck (XWIKI-17886), the language of the (partially) created subwiki was in a Cyrillic language (reproduced locally on my machine).

The issue could not be reproduced on XWiki 12.4.