Hi, There is no facility within LO Writer to apply a readability test on a text document. It would really be a useful feature to include a Flesch-Kincaid tool within Writer.
https://en.wikipedia.org/wiki/Flesch%E2%80%93Kincaid_readability_tests This sounds like it would be more suitable as an extension. Asking UX anyway.
Hmm... the logic and coding needed for these two specific tests are simple--and easily implemented as macro. If integrating in UI it would need to be placed in Tools -> Languages -> Writing Aids. However, I've serious objection to implementing this very U.S. centric feature in the LO core. Far better it be developed as a more generalized extension (providing users multiple tests of language "quality" metrics) and be left to its own merits for development support and adoption.
*** Bug 148807 has been marked as a duplicate of this bug. ***