"Early resolution" is a type of proceeding in circuit (felony) court where "the state" (the local prosecutor's office) believes the cases scheduled have a reasonable chance of being resolved. It is the first formal court proceeding for those who did not have a "first appearance" (aka "initial appearance") in jail, therefore it is relatively "early."
Sometimes a criminal defendant will get a good plea offer at early resolution, sometimes not. If not, she'll want the case to be continued to the next court date. Looking at the whole picture, she may want it continued even if she gets a reasonable offer.
With your sister's trafficking in stolen merchandise/dealing in stolen property charge, the state must prove that your sister knew the property was stolen or should have known. Based on your post, if the state has filed a formal charging document (an "information") than it is confident it can prove beyond a reasonable doubt that your sister is guilty of the crime.
Just because the attorney has not returned calls does not mean the attorney is not helping your sister. If her court-appointed attorney works for the public defender's office, she is not at an automatic disadvantage, but attorneys who work for the public defender's office typically are very busy because they are relatively overworked. Such is not true of the typical private defense attorney.
If unhappy with the court-appointed attorney, your sister is free to call me with any questions or to retain me. Just because she has an open case that is a felony does not mean the cost is prohibitive. Your sister's clean criminal record helps her in that regard, and more importantly, with the state and how this case will be resolved.
The case may be dropped, there may be a plea to a lesser charge, it may go to trial. Your sister deserves an attorney she can trust.
"Early Resolution" is a designated Court date created to allow all of the parties in a Criminal case to meet and attempt to resolve their criminal case "earlier than normal". The accused defendant, their lawyer, a prosecutor and the judge are all assembled in the courtroom at the same time in an effort to resolve the case that day. Defense lawyers are permitted to obtain the discovery materials (Police reports, witness statements, photos, videos, etc.), review that material with their clients, in order to possibly negotiate a favorable resolution of the matter in lieu of a trial.
Not all cases will get resolved at "early resolution" and not all cases are even set for an "early resolution" date.
You should consult with your lawyer to have them explain this process and whether you would benefit from a possible "early resolution" of your case.