Strangely, Eric Blanc doesn’t quote Isaac Deutscher, who argues exactly the opposite.

Here’s what he says in his 1958 interview –“The Tragedy of the Polish Communist Party”

“When the question of the march on Warsaw came up, (the Polish Communists in Moscow) split in a rather paradoxical manner.

On the one hand, the old ‘Luxemburgists’, the ‘opponents of independence’, Radek and Marchlewski, [8] spared no efforts to convince Lenin and the Russian Politburo that the march on Warsaw should not be undertaken, but that peace should be proposed to Poland as soon as Piłsudski’s armies had been chased out of the Ukraine. (They succeeded in winning to their point of view only Trotsky, who was then the People’s Commissar for War.)

On the other hand, the old supporters of independence, former PPS men like Feliks Kon and Łapiński, favoured the Red Army’s march on Warsaw; they maintained that the Polish proletariat was in a state of the utmost revolutionary ferment and would welcome the Red Army as its liberator. “
Deutscher argues that:-

“the Red Army’s march on Warsaw was a much more serious and more damaging moral handicap for the Polish Communist Party than had been all of Rosa Luxemburg’s real or imaginary mistakes taken together.”

https://www.marxists.org/archive/deutscher/1958/polish-tragedy.htm

Blanc’s bibliography also fails to mention Paul Frölich’s well-known biography of Luxemburg, which is far from being uncritical of her views on the Agrarian or National questions in Poland.
see “Rosa Luxemburg, Her life and Work” Gollancz 1940, pps 274-5.

This is curious omission, since Frölich’s life-long partner Rosali Wolfstein was a close friend of Rosa Luxemburg and inherited her papers, which formed the basis for Frölich’s biography – hardly an exercise in hagiography.