Ala Carte is, in all likelihood, not canon. There are many anthology books out there like that (Code Geass, K-ON, Clannad, etc), but it's basically just artists having fun with a franchise and its characters to show their love for it. The stories themselves are usually very silly and so ridiculous that clearly it doesn't fit in the canon. One of the Code Geass shorts had C.C. making Lelouch go on a date with Suzaku in order to gain the support of internet fangirls. Great entertainment, yes, but would something like that ever actually happen in canon? Heck no
