I'm not concerned by that article much at all - key is they dosed daily for six days at what seems to be a high dose (comparable to what has been used for ischemic injury, which is quite a bit higher than for anemia) and saw about a 50% reduction in C1q. I think with the intermittent dosing that FGEN uses this likely would be ameliorated, and certainly it will be with lower doses.
Also a moderate reduction in complement activation is likely a desireable thing for most CKD patients.