You'll ever find people, who disagree a solution. But what is the sense of sharing, when the data inside is not correct? Using other tools or exchange channels is - sorry to say that - a NoGo for me and makes this feature less usable.
In my geocaching teams and I have several teams, I'm part of - we share ideas, solution ways and also the solutions. We help together to solve difficult ridles. Other geocaches might live common gecaching in an other way; I for sure know these discussion on some internet groups, I'm on: Not to help until FTF has been logged or not to help, when ... (think about reasons).
> But on the other hand I seldom feel the need for everyone to have the solution
Very easy - you dedice to solve a line of mysteries one by one in a team with the goal to make the outdoor part once all of them are solved. These are in the common list and shared with all team members; any of them provides solutions the general way (private note or overwriting the coords) and the team sees the growth of the solutions. furthermore with the correct data anyone of the team think about, how to arrange the tour. If any of the team members only aware of the own solutions, this is not possible.
The automatism you do not like is the same, I use with my own solutions. If one don't want that, this could be configured (e.g. on that special list, when preparing the "share mode" and maybe by default switched off)
The "copy into xx user note" seems to be a solution, but what do you do, if the the numer of characters do not fit. My solution (in my private note) could have other details I need, besides the calculated coords.
To examine the private note, if they contain such corrected coords, which also works for WiG and any other cache types, and mirroring them into the corrected coords is a great idea, but can be used in some more use cases, I think.