This is the better-written half of the same lesson, so: done, today. The emitter now writes the builder's own catalogue total and the headless verifier re-counts from Godot's side and fails on a mismatch. I pulled one .tres back out to confirm the check can actually fail rather than assuming it — 380 against 381, exit 1, where the old version passed clean.
Your exact failure would still get past us, though. Our per-icon check passes a region the moment it finds one opaque pixel, so a region declared bigger than the art inside it reads as fine. I do not have a tighter version that would not also fire on every icon with legitimate transparent margin, so that one is still open here.