No, The Canary and Skwarkbox (sp?) clearly aren't "sensible" (by which I assume you mean reality-based) left. They clearly contribute to a milieu where stupidity is tolerated if it's our stupidity. Suggesting this is a false flag is obviously conspiraloon shit.
You can think that yes, there's a problem with antisemitism and Corbyn was a fucking idiot for making those FB comments; but that it may have been raised again at this time by his opponents inside and outside the party to maximise damage before the local elections, after which there may be another coup. And you can think this and believe that of course dealing with antisemitism is more important than Labour Party local election results. Or you can think that this is a false flag funding by an Israeli conspiracy and deny any issues with antisemitism. The latter is a real problem, this stuff needs to be challenged on social media and IRL and ideally no-one in the party should be thinking that nonsense, although I'm under no illusions that some do.