The principal criteria describing a bildungsroman (coming of age) novel can be identified generally as (1) the presence of a central character that is young/childish, in one way or another and (2) depicts a process wherein that character grows, matures, changes or otherwise comes into adulthood. The question to ask is – Does the story depict a formative process for a central character?
“Bildungsroman is the name affixed to those novels that concentrate on the development or education of a central character” (eNotes).
Elizabeth Laird’s novel, A Little Piece of Ground, will qualify as a bildungsroman if we can say that the story of Karim Adouli meets the above-mentioned criteria.
Karim is, indeed, a child. He grows into a new personal and cultural perspective over the course of the novel. His experiences tear him out of any innocence he may have enjoyed and put him face to face with the difficult realities of life under occupation.
Perhaps problematically, this perspective is informed largely by negative feelings and outright hatred. Yet, on a technical level, the emotional content of the characters changes make little difference as to whether or not the novel can be considered as a bildungsroman.
Is A Little Piece of Ground a conventional or common form of bildungsroman? The answer to this question is probably “no.” But is it an example of a bildungsroman, generally speaking? The answer to this question is seems to be “yes.”
To answer this question for yourself as a reader, you have to decide if Karim has been "formed" or "constructed" into a new version of himself by the novel's end. If he is still "under construction" or still in the process of "coming of age" then you might want to argue that the novel does not truly belong to the category of bildungsroman.