Something I would like to point out is this 'bug' is not new. Nor is the awareness of it's existence. It has, after all, been long understood, that if you bring items forward incorrectly they can get "scrambled". What is new is some people have done some testing, (afaik with segregated testing files) brought forth further information that changes a "weird, somewhat novelty, but mostly just annoying accident/bug" into something that can "reroll" items to produce something potentially useable and/or buggy such that it can result in exceeding limits placed on affix ranges/values.
Given that we know how such items are created, that accidentally doing so will be very obvious the the person bringing items forward, and that outright impossible stats on items would more or less be easily spotted in read-outs/screenshots, it shouldn't be hard to make or 'regulate' a rule on this edge case, as necessary.
On the one hand, this isn't much cheesier/sketchier than some of the stuff already possible and accepted in the forums. The most obviously/immediately comparable of which is 107 bugged crafts, which can also result in otherwise impossible values on affix values (e.g. MPK rings, massive LL, recipes that can roll sets/unique instead of just magic/rare, etc..).
On the other hand, it is different, albeit mostly in terms of degree.
For example, the 107/08 stuff is a result of bugs inherent in the in-game crafting process (or different recipe rules), while the buggy rares are a result of a missing intermediate item format (107-109) when changing item formats from (100-106) directly to (110-114), causing a faulty re-randomization of the item. Still a bug with in game code, albiet further removed from 'normal practices'.
Somewhat like... say, a 109 ravenclaw, that in patch is bugged and doesn't use the correct Lv30 exploding arrow value, but when converted to 110+ (and it's new item format) it maintains the Lv30 value, while the patch in question no longer has a bug preventing it from being used. Still, that's one item in particular, rather than a whole host of potential buggy outcomes, and a more organic process.
Or beta runewords maintaining old, clearly-not-intended crazier stats when being forwarded. (Or runes being much more common than 'intended' by HF rushing, etc...)
But you get what I'm getting, at right? Cheese is cheese. This has potential to be cheesier (in degree) than most (though by no means all) accepted practices, but to my mind, it isn't really any worse than any of the other broken stuff time travelling can do. Which, afaik, is already something one aught to report on one's trade/MP profile.
The primary thing that sets this buggy rare thing apart from other timetravel shenanigans, is mostly that it's (relatively) easier to do in larger numbers than it is with crazy crafts, beta runewords, and weird uniques. And that the pool of possible effects/results upon the gear is potentially wider than what is currently understood to be possible with the other things.
While I personally do not think I would bother, I don't really see this as wildly/grossly cheesier or cheatier than things already accepted (and not just the clear 3rd-party-app-required outliers like atma bugging/hotmuling). You're still quite unlikely to get anything that's anything other than a vague novelty. It still a big pain in the butt to do with anything approaching the kind of numbers likely to see any kind of non-novelty result (albiet easier, purely by virtue of the lack of additional limiting factors like rune rarity, or gem/skull availability).
Consider someone pushing
the limits of time travel, or some of the crazy cubed jewelry we've seen over the years. If I'm someone who objects to trading with someone who uses bugged items, I'm not likely to make a distinction between 20+ LL blood crafts, prismatic uniques, or this new thing.
Conversely, nor am I like to draw the line at this new thing, if I don't with things like the aforementioned cube bugs.