According to the article you cited, the CBA says that the terms of the offer sheet become the principal terms of the Standard Player Contract ("SPC"). The CBA goes on to say that the player and the club shall promptly formalize an SPC, "containing: (i) all the Principal Terms ; and (ii) such additional terms as may be agreed upon between the Restricted Free Agent and the Prior Club." As I read that, if they can't agree upon additional terms, they are nevertheless required to finalize an SPC containing the Principal Terms.
According to the article... Nashville has the right to exercise their "first right of refusal" which they did. That is they say they will match the contract. Now comes 11.3 & 11.4:
11.3 Validity and Enforceablility (of SPCs). Except as expressly set forth in Section 11.5 below, no SPC shall be valid or enforceable in any manner whatsoever unless and until it has been filed with Central Registry and approved by the League or the Arbitrator.
11.4 Signing Deadline for Group 2 Free Agent. An SPC for a Group 2 Free Agent will be rejected and will be null and void if it is not signed and filed with Central Registry by 5:00p.m. New York time on December 1 in the then current NHL Season.
No SPC has been signed and filed yet.