What else does "our interference by converting many to Christianity" reasonably mean?

When you say "we (our) converted," "we" is the actor performing the action of conversion. If you intended to give the convert-ee agency don't make them a puppet. The word "interference" also pretty much can only imply "we" were doing something against their will. If people want to do things you helping is not "interference." 

That of course ignores that "we," meaning the the US, Europeans, "the West," or America, had nothing at all to do with the spread of Christianity in the Sudan. The US didn't exist and Christianity was almost unknown outside of Rome, where it was a minor cult among many. The only people who "converted" anyone in the Sudan to Christianity were Sudanese who traded with the ME and saw it there.