For those who are using Emacs, https://github.com/federicotdn/verb provides similar UX, I have been using it as a postman alternative for quite some time.
I have been using https://github.com/jacktasia/dumb-jump to quickly jump to definitions. LSP is hit or miss; in some languages, it works great, while in others, the implementation is not so good. I have been thinking about a middle ground based on Tree-sitter. GitHub uses Tree-sitter to power code navigation, but unfortunately, I can't find anything good that I can use offline. Why is there no ctags equivalent powered by Tree-sitter?
We have a similar use case. All Elixir code base, but need to use Python for ML libraries. We decided to use IPC. Elixir will spawn a process and communicate over stdio. https://github.com/akash-akya/ex_cmd makes it a breeze to stream stdin and stdout. This also has the added benefit of keeping the Python side completely stateless and keeping all the domain logic on the Elixir side. Spawning a process might be slower compared to enqueuing a job, but in our case the job usually takes long enough to make it irrelevant.
ES should be thought of as a json key value store and search engine. The json key value store is fully consistent and supports read after write semantics, refresh is needed for search api. In some cases it does make sense to treat it as a database provided the key value store semantics is enough.
I used it about 7 years ago. Text search was not that heavily used, but we utilized the keyword filter heavily. It's like having a database where you can throw any query at it and it would return a response in reasonable time, because you are just creating an index on all fields.