Not every body will show to all his source code, because they are often much work and brainstorming behind it. Jan makes the source code not viewable at binding the source to yab.
You are right to say, put yab into the bin folder of Haiku (we ask many times, many years... nothing happens, since yab is out), so any open yab source are runable using the yab binary (if the source is made of base of the included yab version).
GitHub: Do that you like, but make it useable, every other way is stupid, because no one comes to try it out or begin development in yab, because the package are broken. Alternativly add a instruction to make the package workable. Give yab, a native development language for Haiku, a chance to alive.
And for the main question: Yes i have interest to take yab alive, so we make the unofficial version of yab. A result of testing and trying, because we are no C++ coders.
It will be fine to get some c++ coders to work on yab for the future releases. The main developers are not active, or we does not know that they are active.
http://www.besly.de: We have many tutorials for yab and much more. We starting a yab mailing list at freelists.org, for some years: http://www.freelists.org/list/yab-dev. We also starting up a IRC Channel on Freenode.org called #yab and #yab-dev, but we have not anough developers to make the channel full any time. If anyone have enough expierience in IRC, please make a bot for the channel
yab FAQ: http://besly.de/menu/search/archiv/dev/yab_faq_eng.html
yab Apps: http://besly.de/menu/search/archiv/misc/yabapps_eng.html
Sorry for bad english