In the response payload, we have the field type that should have an URI reference [RFC3986] that identifies the problem type. Will the EPC provide the URI references to be used in each problem?

Alternatively, could the URIs from the Mozilla Developer Network (MDN) be used?
The VOP API is a relatively basic API, it is not currently planned for the EPC to provide a standardized list of URI references to be used for each type of problem.  

The Mozilla Developer Network (MDN) URIs you mentioned are widely recognized in the development community; however, they are not specific to the Open Banking API framework nor aligned with PSD2 requirements. 

The VOP API WB approved the usage of MDN URI if necessary.