Perhaps I am suggesting something that is obvious: if a solicitor was involved in drawing up the will, there is a chance that the original is held in the solicitor's office.
If people have searched assiduously over a period of six months and failed to find the will, it looks like time to head for the Probate Court for a ruling. If all beneficiaries (those named in the missing will, and those who might stand to inherit under intestacy rules) believe that the will is a true one and that there was no intention to revoke it, then it is likely that the Probate Court will recognise the copy. If there are conflicting opinions, then you can not anticipate the outcome.
Even if the executors intend to act personally, I suggest that they engage a solicitor to help with bringing the matter to the Probate Court.