So ... KNYFE's card says Agent of Filter (admittedly, crossed out) .... however
Does that make her an Agent?
Does she benifit from Lock Down, Warden Hoeffle, and isnt target by other agents who say 'Non Agent Card'? Can the Rogue destroy her at the start of the environment turn?
I'm guessing this is not the case but... its still amusing to play that way.
If anything it might be more that she would have a nemesis condition with any FILTER agents encountered.
It's the same issue as the issue of whether or not Golemn Unity should be healed by Inspired Repair. Although that would be thematically appropriate, Hero cards don't have keywords and can not be affected by things that don't specifically target Heroes or Hero targets.
Villain characters have keywords, why not heroes? I, too, would like to see Mechanical Golem on Golem Unity and Agent on KNYFE. 
I really don't. Imprisoned Rogue would suck…
Besides, I think she's an Ex-Agent - she's not currently an Agent.
To be fair keywords on villain cards appear in the apporriate location and inside a the standard keyword box. There is not "Box of Keywords" on the heroes, just their name and title which is all roughly together at the top of the card.
Finally worked out why Golem Unity having a Mechanical Golem keyword would be a bad idea, her Scrap Metal card.