It’s fair to call it stalinism / maoism etc. And I also dislike associating Marx that closely with them. The Marx parts of Marxism are pretty tough to have issue with. Engles, Lenin, Stalin, Mao etc are where a lot of the backward reductive and damaging stuff comes from. But it’s about hitting them where they live. And these days they identify as ML.
And yeah I agree. Despite making wildly flawed ideology I absolutely believe Engels and Lenin had good intentions. And despite all of them, including Stalin. Russia absolutely had successes. I can’t say it was enough to out weigh the failures. Similar things can be said about China too. Though xi jinping will mark the end of all that.
The last bit, I don’t think I can go in for. If it was capitalists calling them ML and them calling themselves something else then perhaps. But it’s what they largely self identify as. The thing to remember however, is that it’s the ideas that are important. Not necessarily the names. Would Marx want to be associated with future systems based on his concepts? Sure. Would he not want it implemented without his name. That I doubt.