Giving the length of this page and how recurring the problems that exist here, are the extension devs (all from WMF I believe) working on a way to make it easier (not by way of a colossal tool like vagrant)?
Topic on Extension talk:Scribunto
Judging from Scribunto's board on Phabricator, I don't believe there's any such effort at the moment. Patches welcome. :)
Most of the problems people have here are either from not correctly following the instructions we already have, or from trying to use a stupidly locked-down Web host. Neither of those are really things that we can fix.