I don't think anybody in the PC-Engine community is going to receive any cease and desist letters because they all decided to team up and port a game to their system. Osman or not. You might foresee problems there, but I decidedly do not. That might just be programmer paranoia. 
Sure, I know that you didn't say that.
I could easily just be being totally paranoid ... but in a world where Nintendo takes down people's YouTube channels for posting the "wrong" video of their copyrighted materials, then you never know.
OTOH, there's the argument that if nobody has stopped Tobias and PCEWorks, then anything-goes.
The truth is probably somewhere in between, where it would depend upon which arcade game you chose to port, and how much attention you drew to it (more attention -> more chance for trouble).
I think the main problem with the PC-Engine community is there is little to no cohesion or teamwork, for the most part.
Yep, it's been a little surprising to me just how little there is in the way of "community" resources, but when it comes to folks actually collaborating on a single project, then I'm a lot less surprised.
Most 4th-gen games that I know of BITD were mostly one programmer, and one artist, for 80% of the work, with maybe another artist if you had enough work to split backgrounds and sprites between 2 different people.
You might have had another pair added part-way-through, to do things like the menus, cinematics, or stuff like that.
Smaller teams just worked better than throwing lots of semi-interested folks at the same project together and then trying to figure out who-does-what-sprite-but-let's-make-them-all-look-consistent.
Collaborative code-development is difficult-enough in the professional world ... I can only see it being an absolute nightmare in a part-time hobby project.
From my POV, the problem isn't one of getting a lot of people to collaborate together on one project, it's more one of needing to have more people doing more projects.
Peer-pressure has always been a wonderful motivator for developers.
Even if folks aren't on the same project ... just having the "community" vibe being that stuff-is-getting-done, and constantly posting updates, helps give everyone else the motivation to not appear to fall behind and just spend the evening on the couch instead.
I've tried to make Uli's HuC easily accessible for folks ... and have received mostly apathy except for DK & Gredler, and even they probably wouldn't have used it if the old HuC hadn't broken on them.
It's only because of their willingness to actually use it that bugs have been found and fixed.
It's the same with Huzak.
If it wasn't for Michirin9801's large portfolio of tracks to test it with, and her willingness to be a part of the process and to listen to the results and point out problems, then it wouldn't be anywhere near as far-along as it is.
But, the reality here in the PCE community is that there just aren't a lot of active developers/teams, and I don't really have any clue of how or even if, that's going to change.
Although, I do have to say that the work that Sarumaru and the Henshin Engine team are putting into their project is really inspiring; and their ability to actually get a spotlight on it, and get some public buzz, has probably done more to raise the PCE's development profile than anything else that I've seen in the last xxx years.
