Complex sentence: Political reactionaries are at the right-wing of a political spectrum; yet, reactionary ideologies can be radical, in the sense of political extremism, in service to re-establishing the "status quo ante".
Split into simpler sentences: Political reactionaries are largely found on the right-wing of a political spectrum. Reactionary ideologies can also be radical, in the sense of political extremism, in service to re-establishing the "status quo ante".