is there any estimate on completion % of chapter 3
Dev occasionally puts out free posts on patreon to look at so I'd recommend at least using that "joining for free" thing they have there and sometimes checking patreon for a free post.
Most recent one says chapter 3 is in the FINAL stages of development. It's being read over, edited, suggestions are being given on what to change, proof reading, testing, translating, that type of stuff.