I don't know how often in the life of a file a cover has to be imported from such varying paths.
So I would think that simply an action group with 2 (or more) actions that import covers from various folder depths would be a good way.
... and that such a folder is
does not seem to be true as the linked thread looks for covers in
I see in your suggestion the problem that you would have to switch on an off that recursion if you want to get the desired hits if you have several picture files in different folder depths.
And if you do that, you could alternatively adapt the path ...
So I think until your request becomes a feature, there are a number of workarounds