The question is, can you even find a decent source in that area hat's not overrun with hard-right ideology?

In Germany we for example have "expert" of the horseshoe theory Eckhard Jesse going through the media who loves to remind people of the evils of left extremism, only to then (oh surprise) say that right-wing extremism was "more phantom than reality", the rise of the neonazi infested far-right Trump/Brexit aligned AfD was a "sign of normalisation", and that Germany had to stop its "self-torturing ways of coping with its past".

Frankly, any organisation dedicating itself to "Communist Crime" usually comes with similar motives. Credibly research facilities obviously aren't afraid to work on the topic, but are usually not exclusively dedicated to it.