Front-end pipeline (FEP) configuration can only be set at root level of the site in content hierarchy. Also, the sling:configs can be added directly under /conf and not a node beneath.
Use-case:
We have grouped our sites and are looking for separate front end pipelines per site.
e.g. /content/group1/site1, /content/group1/site2, /content/group2/site1, /content/group2/site2
This has been reported to the engineering under the internal reference SITES-16565. The product team will triage this request to verify feasibility based on the prioritization model. This post will be updated according to the Jira request status.