Thanks.

What about the non-optional id and title concerns?

Using the plugin without authentication also currently does this instead of failing gracefully:

$ streamlink https://network.wwe.com/live/278763
Enter wwenetwork email:
Enter wwenetwork password:
[cli][info] Found matching plugin wwenetwork for URL https://network.wwe.com/live/278763
error: Unable to open URL: https://dce-frontoffice.imggaming.com/api/v2/login (422 Client Error:  for url: https://dce-frontoffice.imggaming.com/api/v2/login)

With invalid auth data:

$ streamlink https://network.wwe.com/live/278763
Enter wwenetwork email: invalid
Enter wwenetwork password:
[cli][info] Found matching plugin wwenetwork for URL https://network.wwe.com/live/278763
error: Unable to validate response text: ValidationError(AnySchema):
  ValidationError(dict):
    Unable to validate value of key 'messages'
    Context(ListSchema):
      Length of list (3) does not match expectation (1)
  ValidationError(dict):
    Key 'authorisationToken' not found in <{'status': 404, 'code': 'NOT_FOUND', 'messages': ['fail...>

With no auth data and 422 added to acceptable_status:

$ streamlink https://network.wwe.com/live/278763
Enter wwenetwork email:
Enter wwenetwork password:
[cli][info] Found matching plugin wwenetwork for URL https://network.wwe.com/live/278763
error: Unable to validate response text: ValidationError(AnySchema):
  ValidationError(dict):
    Unable to validate value of key 'messages'
    Context(ListSchema):
      Length of list (2) does not match expectation (1)
  ValidationError(dict):
    Key 'authorisationToken' not found in <{'status': 422, 'code': '422', 'messages': ['passwordIs...>

diff --git a/src/streamlink/plugins/wwenetwork.py b/src/streamlink/plugins/wwenetwork.py
index ea1f4869..86414e49 100644
--- a/src/streamlink/plugins/wwenetwork.py
+++ b/src/streamlink/plugins/wwenetwork.py
@@ -52,14 +52,14 @@ class WWENetwork(Plugin):
     def _login(self, email, password):
         success, data = self.session.http.post(
             self._API_LOGIN_URL,
-            acceptable_status=(200, 401, 404),
+            acceptable_status=(200, 401, 404, 422),
             json={"id": email, "secret": password},
             headers=self._API_HEADERS,
             schema=validate.Schema(
                 validate.parse_json(),
                 validate.any(
                     validate.all(
-                        {"messages": validate.list(str)},
+                        {"messages": [str]},
                         validate.get(("messages", 0)),
                         validate.transform(lambda data: (False, data)),
                     ),
@@ -88,7 +88,7 @@ class WWENetwork(Plugin):
                 validate.parse_json(),
                 validate.any(
                     validate.all(
-                        {"messages": validate.list(str)},
+                        {"messages": [str]},
                         validate.get(("messages", 0)),
                         validate.transform(lambda message: (False, message)),
                     ),

$ streamlink https://network.wwe.com/live/278763
Enter wwenetwork email:
Enter wwenetwork password:
[cli][info] Found matching plugin wwenetwork for URL https://network.wwe.com/live/278763
[plugins.wwenetwork][error] passwordIsRequired
error: No playable streams found on this URL: https://network.wwe.com/live/278763

$ streamlink https://network.wwe.com/live/278763
Enter wwenetwork email: invalid
Enter wwenetwork password:
[cli][info] Found matching plugin wwenetwork for URL https://network.wwe.com/live/278763
[plugins.wwenetwork][error] failedAuthentication
error: No playable streams found on this URL: https://network.wwe.com/live/278763