Luxemburg and Serge's criticisms of some of the Bolsheviks' tactical choices in the maelstrom of an unprecedented situation cannot be extrapolated into criticisms either of the 1917 revolution in totality or the idea of revolution itself.
I haven't read the Jacobin book, but if social-democrats (is that what Schwartz is? I don't know) are instrumentalising Luxemburg and Serge in the service of a reformist critique of revolution, even if they recognise that Luxemburg and Serge were themselves unambiguously "revolutionaries", that is very disingenuous indeed.
Also, to read that the book hails Mao as someone who should be acknowledged as a representative of any type of legitimately "socialist" politics is disappointing. Why not Stalin too, then?