The total number of subpages on Meta-Wiki created under the path WikiLearn/Courses is 279 with translate-messagebundle, but I only see 21 message bundle groups on Special:Translate.
Unfortunately at this point, we don't have logging enabled for UpdateMessageBundleJob. I still checked Logstash for what logs are present regarding this issue and I see the following errors:
Non-boolean result returned by job: UpdateMessageBundle
I see 21 of these errors for pages with title prefix WikiLearn/Courses which matches the number of message bundle groups created.
So it seems that UpdateMessageBundleJobs were not created for the remaining pages with content model translate-messagebundle.
We need to identify whats going wrong here.