I debugged this to see where the Com_sprintf overflow error was coming from. It turns out your directory structure is rather large and pushing the limits of the q2 path sizes (currently 64 characters).
When it tries to add the language in (since there can be subdirectories for languages), the result is this:
"menus/openlauncher_v03/system/V06_F0RC3/english/some_menu_name"
This sometimes gets truncated, though it's still OK in the end, since there is no language sub-version of the menu, but it prints out the error at the console.
You can shorten your directory path quite a bit, and it should prevent this issue. Ex:
"menus/openmenu/v06"
I can see about bumping up the path sizes in the future, but I'm not sure what side effects this may have.