**** General comments

The ietf-l2vpn-ntw module with about 400 data nodes represents an impressive amount of work. Its size, however, raises some concerns in terms of manageability. For example, if the ITU-T Y-1731 recommendation ever gets updated (I don't know how likely this is), the module will have to be updated. I would therefore suggest to consider factoring out such parts into separate modules.

Apart from that, the YANG modules are in a good shape. 

**** Specific comments

***** Instance data examples

The appendices A.1--A.6 contain examples of instance data for six different use cases. This would be laudable, but only if the examples were valid according to the data model schema. It seems that the examples were not updated during the data model development. It is necessary to validate the examples using the available tools such as yanglint or Yangson, and correct all errors. Here is a non-exhaustive list of problems in the example of appendix A.1:
- The top-level container "ietf-l2vpn-ntw:l2vpn-ntw" is missing, which complicates the use of validation tools.
- "vpn-service" list contains "vpn-description" leaf, not "description".
- "global-parameters-profile" list contains "svc-mtu" leaf, not "mtu".
- The value of "global-parameters-profile/rd-suffix" should be uint16, not string (e.g. 1 rather than "1"). Similarly, "vpn-target/id" is uint8, not string.
- Container "vpn-targets" encapsulating "vpn-target" list doesn't exist in the schema.
- "vpn-target/route-targets" is defined as a list, but its instance value is given as ["0:65550:1"] (it probably used to be a leaf-list).
- Inside "vpn-service" list, the schema defines "vpn-nodes" container encapsulating "vpn-node" list. This container is missing in the example.

***** RFC 8792 line folding

My reading of sec. 7.1.1 in RFC 8792 is that each text chunk that uses the single backslash strategy should be preceded with the header

NOTE: '\' line wrapping per RFC 8792

**** Nits

- The naming of groupings is inconsistent: "cfm-802-grouping" versus e.g. "y-1731". I'd suggest to remove the "-grouping" suffix in the former.