While all of the above concerns are 100% valid, it should be mentioned that the actual offense involved is distribution.
Except in some oddball cases, end users do not sign ToS or license agreements to merely USE mods; we simply download the mod and install it.
Crucially, many of us edit mods we've downloaded - to alter droprates, tags, functionality, balance, etc. Doing so is not a misuse of mods or assets; this is how modding works! It is neither a legal or commercial violation (which would be absurd). Updating a mod to maintain functionality falls well within acceptable actions an end user may take.
It is only if we wish to distribute "our" revised version of said mod to share with others, then the right thing to do is to ask the original modder for permission. It's also worth bearing in mind that even unchanged mods may not be distributed or reused in other distributed content without permission! Again, the issue is distribution, not alteration.
This is why I'm more interested in a general guide for updating mothballed mods. Give players the tools they need to do things which are legitimate and permissible.