I could find no such list.

I also can't imagine any real use for a complete list, unless you're deliberately attempting to display every possible error code for entertainment. 😛

When people can't find their Q-Code in the manual (or they simply don't bother to read the manual) they always specify their Q-Code while asking what it means and how to fix it - you might find some "missing" Q-Codes revealed/explained in the responses to their questions.

I've found that ASUS has a tendency to recycle their design blocks (in hardware and in firmware), modifying and updating and optimizing each version and revision as needed for each specific platform (re-)release. This isn't a bad thing, it saves time and money and effort, it allows them to build upon proven tech they already understand intimately instead of wasting their efforts figuring out how to invent the wheel from scratch again and again (and engineers always have to work within the many restrictions imposed by their bosses, shareholders, competitors, budgets, timelines, supply chains, regulatory protocols, marketing teams, and customer demands). In practice this means that the latest-and-greatest ASUS tech always packs a bunch of (unused?) legacy ASUS tech: undocumented Q-Codes for newer ASUS products sometimes turn up in the documentation for older ASUS products.

I've also found that the overwhelming majority of "missing" Q-Codes (in my R5E firmware, anyhow) are in fact not present and thus could never be displayed. Although I admit my examinations/analyses of R5E BIOS images were not at all exhaustive or complete. ROG mobos (probably) also run additional (proprietary and code-locked) firmware in their magical "ROG Chip", although I don't think any of it relates to the Q-Code display (which seems to be fully defined in the UEFI/BIOS images).

From time to time people ask about strange (non-hexadecimal, non-readable) Q-Codes which actually turn out to be some sort of malfunction in the Q-Code module or even in the LEDs themselves. Adding these one-of-a-kind sorts of things to the list would be meaningless.