As to Record Layer’s support for text indexes, most of our docs are I think in the TextIndexMaintainer, though it also looks like there are some Javadoc rendering bugs on that page (at least at the current version) that someone should probably fix (and expand upon).
It has basic search capability with a pluggable serializer. It’s more optimized for maintaining many little text indexes (e.g., maintaining many indexes over relatively small copora instead of a relatively small number of indexes over a very large corpus), so it doesn’t do things like cache results as aggressively as other text search solutions, but it does offer transactional updates with documents inserted into the record store, which is nice. (Note also that updates are likely to conflict, so it’s not super great if you need to support adding a bunch of documents in parallel.)
I guess I can answer specific questions about the capabilities of the text index if there are more questions.