Please understand first and foremost I am not an attorney and I would need to actually see the document to be sure.
In a short sale situation usually "release" DOES NOT mean the lender is giving up their right to pursue for a deficiency after short sale. It will allow the short sale to be completed however.
For it to be a full cancellation of debt the wording usually goes something like "full satisfaction" with language then clarifying that the debt is settled. Every lender is different but that is the bottom line for what you want.
I can only hope your listing agent knows what they are doing, because this is short sale 101 on the differences between release and satisfaction. Wells Fargo is pretty bad about pursuing sellers immediately, but certainly it is not a given.