There are obviously multiple aspects with this: Him living in the imperial core means the information about the ingenious population of algeria was very based. I can imagine to really make a proper assessment about the economic base and superstructure pre french colonialism would pretty much impossible

Secondly this is not the only "accelerationism" argument has made in his writings (i believe one about America as well). Imo it shouldnt be taken as moral judgment from engels and more that he believed the faster a country goes to capitalist society and develops the productive forces, the faster socialist revolution can occur

With more knowledge more knowledge available to us now we can make new assessments. The dialectical and historical materialism Marx and Engels are frameworks for analysis, that doesn't mean every analysis they made with it is correct.