? Luxembourg supported armed uprisings against the democratic SPD government.
Nope - there was no democratic SPD government - the SPD and USPD had formed a provisional government after a popular revolution, but the SPD was ready to hand over power to the militarist right (or at least, have a de-facto power sharing agreement). So, the uprsing was to resist the return to power of the old capitalist, militarist elite, even if their rule would, for some time, take the form of "democratic constitutionalism."
(Didn't last all that long - so there is a direct line from the SPD suppression of the spartacist uprising to rise the of the NSDAP)
