I'm updating my translation, and here are some comments:

No starting capital letter:
> the uninstaller could not find registry entries for GCompris.$\rIt is likely that another user installed this application.

Naming:
The images are from wiki commons
Isn't that "Wikimedia Commons"?


board1_6.xml.in mentions "Entrance Hall of Saint-Paul Hospital", just like "board1_0.xml.in" with this URL:
http://commons.wikimedia.org/wiki/File:Van_Gogh_The_Night_Cafe.jpg 
and similar filenames, which looks wrong. Is that maybe a mistake?


../src/missing_letter-activity/missingletter_config.c:95
It represent the letter to search. 
represent -> represents


No final full stop:
Enter here the letter that will be proposed. The first letter here must be the solution


These ones uses French punctuation spacing:
Bellini : Pala di pesaro
Dürer : Lion
Pieter Brugel : Harvest