Firstly, not all animals that group have a specific name, in these cases, they are just called 'groups'. It is not automatic, therefore, that panthers would have their own term anyway. Secondly, many group names are rather obscure and have no underlying basis for the name, they are quite arbitrarily applied. For this reason, there is no basis for assigning a new name to a panther that follows any existing rules or conventions on naming.
Nonetheless, there in fact is at least one name I know of that applies to a 'panther'. A panther may refer to a leopard, jaguar or puma. Leopard groups are known as lepes or leaps. I have vaguely heard of a jaguar group being called a 'jamboree', but who knows. As for the puma, I have never heard a name for them.