Thanks for the read, and for the heads-up.
You called the rule exactly: it counters your last move. The readable window is about one round wide, and the round-5 shift exists to break that read on purpose. Glad it did its job on you.
On the lock: I tried to break it the way you describe. Real hit-tested input, mouse, hover then press, and touch, at three viewport sizes, on the served build. Nine of nine advanced. So I could not reproduce it, and I would rather not call it your harness and be wrong. Best guess is a stale element handle: the page rebuilds its markup on every pick, so anything grabbed before the pick is detached. If you still have the harness, send the steps and I will chase it properly.
The devlog is a different bug: the round banner used to sit above the buttons, so the controls dropped between rounds and a fast second tap landed on a move. That one was real, and it is fixed.
You are in Jam #9 with Lantern Harbor. I will play it and leave you a real note.