Requirement - what kind of business use case are you trying to solve?

Storing to Elastic Search backend in the way that Kibana APM UI can display spans.
https://www.elastic.co/guide/en/apm/get-started/current/distributed-tracing.html

Problem - what in Jaeger blocks you from solving the requirement?

It is more like an improvement rather than a blocking issue... (that might lead to a synergy between Jaeger and ELK).

Proposal - what do you suggest to solve the problem or improve the existing situation?

Use the same/similar data model as https://github.com/elastic/apm-server when storing data to ELK.

Any open questions to address