only, to think about it....
it is not possible, to build a TWIG-Backend-Theme without changes in the core.
a "core-module" (see part of the name = core) is part of the core and part of the package. Of Course, i can build a twig-based version of a core-module, but the developers needs the same time, to check my result, line by line. The same for some advanced function in working modules like news etc. i add for the news module in the past a special block for some autor infos, like contact via phone, email, autor picture etc, maybe, you know it from newspaper pages, but it is my private version, not possible, to make a publish version, because, it's a core module. I can change the module name and use it as 3th-Party-module, but it make no sense for me. Better solution (in my eyes): add this functions in one of the next version of the news-module, switchable in the module settings or something like that.
Another example: i add a extended search function in the foldergallery. in the actual published version, you can search for a picture title or the picture description, if in use. But if you dont use this title or descriptions, you get no results for something from the foldergallery. I add fields for gallery description, location, eventstart & -end, termininfo, autorinfo etc. Is it a good idea? for my usage: YES, but for all? Not sure.
I build a lot of tools and page module with twig in my own style. It has a special folderstructure and use everytime the latest and newest WB-functions, so i'm sure, i can use this module also in the future of wb without problems.
my problem: is my way also the way from WB? can i use my structure as modell for other modules too? From my view, is this the main problem: you need an example module (like the old Hello-World-Module). if i read the postings, i see a lot of activist's, People who sacrifice their free time to build something new, but everybody use a own way. This can be a problem in the future, because, not every solution will work in the future or is a good solution for WB.
i've access to the newest testversion of wb and with every new version, i check at first, what is new. Yeah, my modules works with this version, but is it possible, to make something better? Is there a new function somewhere inside of the core? But what is, if somebody say's, my way is not our way, is not the way from WB? i can put all my modules into the basket (a lot of modules, the first one was from 2015) or i use it for my own. I've a lot of friends or customers with this modules. What can i do? Delete this, it will not longer work? Not possible for me to build new versions of this modules in a new code style, if needed. And thats, why we need some module guidelines.
a very simple example is the wb-intern function get_user_id(), changed in the newer WB-Versions to getUserId(). A lot of modules use this code, to get the user-id from the actual user for the question: is this the superadmin or not.
Simple, to change the code for me , but there are a lot of users with some problems about this in the future. you've to fix nearly every module in the download-area for this
maybe the project-page
is a solution for that, specially for the core modules and to add there some idea's, because, the core modules are developed by Dietmar.
i remember, that i show a twig-version in my module style from the output-filter-module in the past (long time ago), but it was a wrong time, WB was not ready for this. if i see the actual version of this module, i must say, my way was not wrong. The module has now some newer features, but the structure was right and thats, what i mean. Its simple, to use this module as guideline for the admintools and build the used admin tools in twig-based structure, but if everybody use a own solution, it will not work and that is a waste of work and effort