When a user wants to post their first question here, are they told that our sister site English Language Learners exists and they should consider which of the two sites would be most appropriate for their question?
If not, should this be the case?
When a user wants to post their first question here, are they told that our sister site English Language Learners exists […]?
As a matter of fact they are, on the right hand side of the Ask a question page there is a notice. But whether new contributors notice or acknowledge its existence, despite the bold formatting and the link in blue, is open to debate.
If your question is about learning English, ask it on ELL instead.