How does this book present a counter-colonial view of Islamic tradition?
Your question is a bit cryptic, in that the term "counter-colonial" is rarely used, but I can definitely explain how Ambiguous Adventure presents Islamic tradition in a way that is against colonialism. In truth, the novel lives up to its name in that it end none of the major question of East vs. West answered. The view that you call "counter-colonial" is absolutely ingrained within the plot of this complex novel.
The plight of the Peul in Senegal is embodied in the character of Samba who is the heir to the Diallobe family. He is being taught the Koran by Thierno and, at the beginning of the novel, immerses himself in the traditional Islamic traditions.
This is where colonialism appears.
The French are building their own schools, taking students away from their traditional Islamic teachers, trying to assimilate the defeated Diallobe into French society. Samba's aunt wants Samba to be a role model that will lead the Diallobe family into prosperity through French education. Mostly because of his aunt, Samba is enrolled in one of the very "Western" French schools. After reciting from the Koran (indicating his previous formal Islamic training), Samba begins school.
Let the westernization of Samba begin.
Samba is a natural at these "Western" subjects. He excels in history, french, etc. Samba becomes so entrenched in doing well that he neglects his study of the Islamic faith in order to better understand Western values. Even though Samba's father knows the separation between the East and the West has ended, he is still worried for his son.
[Samba's father speaks] of this egotism which the West is scattering abroad.
The second part of the novel shows an adult Samba as an academic success, but struggling with his devout Senegalese Muslim faith. He studies Protestantism and history all the way through Marxism and, in doing so, rejects all materialism; however, he still feels his faith slipping away. When Samba writes about this to his dad, he is sent home to Senegal.
Unfortunately, back in Senegal, Samba no longer fits in. He is too "Westernized." His old teacher, Thierno, has already died and the new teacher is advocating for the schools run by the French. Lost in doubt, Samba can't bring himself to pray in front of Thierno's grave and is stabbed through a misunderstanding as to Samba's hesitation. Through Samba's tragic death, he is united back with traditional Islam and away from the corruption of the French colonization; however, now that Samba is dead, he can no longer help the Diallobe deal with the current colonization struggles!
Thus, we can see that this novel deals with an "adventure in ideas" in regards to Samba as he becomes more and more disillusioned with colonialism and its worldview as he studies more and more philosophy influenced by the French (and only regains traditionalism through his death). In a sense, the despairing Samba is a product of colonialism. This causes a big issue, of course, for the French have colonized and are now "almost" succeeding to assimilate the native peoples of Senegal and other areas of West Africa.