Those theses state that “the entire policy of the Communist International on the national and colonial questions must be based primarily upon uniting the proletarians and toiling masses of all nations and countries in common revolutionary struggle to overthrow the landowners and the bourgeoisie. Only such a unification will guarantee victory over capitalism, without which it is impossible to abolish national oppression and inequality.” (Lenin’s theses, para. 4)

And, in Roy’s “supplementary” theses, para. 7: “For the overthrow of foreign imperialism, thefirst step towards revolution in the colonies, the cooperation of the bourgeois-nationalist elements is useful. But the foremost and necessary task is the formation of Communist parties that will organize the peasants and workers and lead them to the revolution and the establishment of soviet republics.”

As you say, the Brussels conference was an attempt by “a wing” of the CI — let’s be clear, the Stalinist “wing” or faction — to “structure” anti-colonial unity as “a unified, ongoing effort.” You acknowledge that the presence of invitees from prominent reformist bourgeois movements meant that the LAI was “not a united front of the type proposed by the Comintern since 1921.” In fact, the attempt to structure them into a common organization was not just “questionable,” it was a betrayal of the 2nd Congress theses — tragically proven by the massacre of Chinese workers and CP cadres carried out by the Guomintang just weeks following the LAI founding congress attended by Guomintang leaders. It was the Stalin faction that had forced the Chinese CP to enter the Guomintang and submit to its political leadership.

The LAI was not just a victim of Stalin’s ultraleft Third Period; its very conception was fundamentally flawed from the outset. Trotsky correctly characterized it at the time as a “masquerade” and a “decorative” cover for a class-collaborationist orientation to bourgeois nationalist leaderships.

For an authentic anti-imperialism, consider this article by Peruvian Marxist José Carlos Mariátegui, written in 1929 in opposition to the APRA, the would-be “Latin American Kuomintang” whose leaders had attended the Brussels LAI conference: “Anti-Imperialist Viewpoint,” https://www.marxists.org/archive/mariateg/works/1929-ai.htm.

“For us, anti-imperialism does not and cannot constitute, by itself a political program for a mass movement capable of conquering state power. Anti-imperialism, even if it could mobilize the nationalist bourgeoisie and petty bourgeoisie on the side of the worker and peasant masses (and we have already definitively denied this possibility), does not annul class antagonisms nor suppress different class interests….

“Without ruling out the use of any type of anti-imperialist agitation or any action to mobilize those social sectors that might eventually join the struggle, our mission is to explain to and show the masses that only the socialist revolution can stand as a definitive and real barrier to the advance of imperialism.”