Could a Marxist claim that interpreting the world is all that a Marxist vanguard can do, but that the working class can still change it? Marx, quite famously, said that
philosophers have only interpreted the world, in various ways; the point is to change it.
Note, I hope that a Marxist "vanguard" could claim that, because I do not think that individuals, even individual parties, make history. Such that, my advice to any genuine Marxist would be to interpret the world: and hope that the working class changes it.
Whether or not Marx felt that he was changing the world, or merely interpreting it, the alternative is substitutionist, as well as I think quite deluded.