After some hesitation, I have deployed Prosilver Special Edition on the Wesnoth.org forums, with multiple changes meant to make it more similar to mainline Prosilver in terms of layout. Wesnoth’s custom Prosilver changes have also been applied on our copy of Prosilver SE.
In fact, Prosilver SE as used in Wesnoth.org depends completely on the main Prosilver template rather than its own partial template set, and it also replaces the default Prosilver theme/stylesheets and imagesets, since otherwise very few people would choose to use it. Besides, OAB.
Of course, further changes are not unlikely to occur, depending both on the users’ feedback and my own testing experiences.