It is a very difficult one. I don't think that there are such specialists. I am sure that there are arbitrators who could make a ruling on a dispute to avoid going to court. But it seems that you need more than this.
Do both sides trust the accountant or auditor as independent? If not, they should both seek an accountant as an advisor and the accountants should be able to negotiate a deal for them. If they fail to agree a deal, they would appoint an arbitrator to decide.
As it is probably going to be an ongoing issue, it might be a good idea to appoint an independent chair to the board of the company.
Brendan