Whether you agree or not, vague language is a valid concern. It reads directly on how courts will struggle to interpret the law and how the new mechanisms it will institute may be abused.
The challenge to the reasonable request you are making is timing. The bill could go to a floor vote as early as next week. There isn’t a lot of time to pressure its sponsors to hear amendments, an avenue that was in fact explored but ultimately failed with SOPA and PIPA.
I do share your concerns that too often putting out very general calls for opposing new legislation invites eventual skepticism from the wider audience of online users to which these appeals are targeted. That doesn’t mean that there are not valid problems with CISPA.
I would suggest that in addition to asking good, critical questions about how EFF is acting to oppose a problematic bill, you also pose your thoughts as a more general question: if the outcome is so valid (which is highly debatable for CISPA) then why don’t the sponsors allow more time for debate, relying on the strength of their arguments rather than a rush to enact a problematic bill?
The willingness to compromise you ask for requires time and opportunity provided by the sponsors to be seen as worth pursuing by hackers and other concerned netizens. EFF is not in a position to directly propose amendments, either. Doing so usually requires an ally within Congress, something we are lacking as those that opposed SOPA and PIPA and worked to make room for debate and deliberation have been convinced by the vague threats and poor reasoning around security risks motivating this bill. (Bruce Schneier’s books and blog are excellent, accessible resources on how we make poor decisions when it comes to risk.)
If you are not already, I suggest you read Mike Masnick’s coverage of the questions around CISPA as being a bit more thoughtful. In his most recent post, he does give credit to the sponsors for considering amendments but correctly points out that they are not receptive to those suggested by the public, only technology companies.