So what you're really saying is that the issue is that there is no standard (within Bitcoin) for entropy whitening and therefore you shouldn't do it. That makes sense, though you should realize you're not doing it and protect your mnemonic (and dice) with more care because any bias is directly visible in recorded data - which is why we whiten. (Perhaps you can counter this by, after you generated the entropy, destroying the dice, so that you can't ever use the same set again. Static bias = vuln.)

There's a "standard" inside NIST SP 800-90B (section 3.1.5.1.1, pdf-page 23) - they call it "conditioning" there, but it's sparse, it basically just says "hash it, see our list of certified hashing mechanisms". There are a bunch of random papers, like 2208.11935 but these are all working from an input granularity larger than or equal to the hash function, so it wouldn't be enough for dice where the granularity is smaller (padding is not your friend.)

Maybe it would be good to build a standard, and at least document the tradeoffs.