csqc is not ssqc. that is the entities in ssqc only exist in csqc if you create them, either through the SendEntity stuff or from spawn() in the csqc. Either way you need to explicitly set the classname within csqc or it'll be blank.
findradius works purely on origin (and usually solidity), it doesn't care about self (and will thus return it as it would any other entity), but will ignore world.