This thread assumes that "cultural appropriation" is a legitimate concept in western society.
I'm not sure if i qualify here.
I have previously asserted that "cultural appropriation" can exist as a negative and one should be mindful of it and i have taken the affirmative ("pro sjw" if you will) position in some thread once - i believe the matter at hand may have been belly dancing.
On the other hand i am critical of most claims of "cultural appropriation" as a negative and am habitually critical of most of the people who like to talk about "cultural appropriation" as a negative.
You obviously allready know this, but i feel intellectual honesty requires that i disclaim my obviously limited credibility on this vis a vis the premises you want to see accepted for argument's sake.
TMIT's objection is valid.
You are asking for a "solution". I strongly suspect for us to agree on one we'd have to have at least some loose and tacit consensus on what cultural appropriation actually is and when it is bad (i take it to be an implied premise of you original post that it sometimes is and i doubt there are many people who'd claim that it never is).
My off-hand first swing would be something like this:
1. There has to be a transfer of practice.
2. The power gradient is a large determining factor regarding the actual damage, so it helps if there is one and if it's big.
3. There has to be a mismatch between adoption of the practice and adoption of understanding. Such as:
a) The adopting party vastly changes the thing but believes it to be still authentic or alternatively forgets they adopted it and believe it to be entirely their own product.
b) reversely the adopting party conserves (to the point of obsession) the thing for authenticities sake but doesn't understand it; i.e. said party doesn't appreciate the purpose but is in essence maintaining a larping prop.
c) There can be a variety of gross mismatches on other dimensions, i suppose.
In my experience the disagreement between me and the people i label SJWs is twofold:
One disagreement seems to be that they are absolutist about the second criterion. I.e. they deem it virtually impossible for a more powerful party to be transgressed against (or for that to result in actual damage). I don't agree with that and merely see power gradients as a strong mitigating/escalating factor.
The other one is that they usually don't accept the third criterion. At all.
I could belabor that point now but i suspect that you at least tangentially agree with me on that point anyway.