As for Lingua Franca Nova, I haven't been able to find any discussion or decision (neither in the LangCom archives, nor on Meta) about treating its external wiki as a test project. All I know is that it has been
present in the Incubator, but I have no idea whether that was really the place where "it" happened. What I do know, however, is that a
similar request has been made for Toki Pona:
'This proposal is slightly unusual in that it seeks to have an external wiki considered as the "test project". I have cleared with a LangCom member that, at least in principle, this is possible. (If upon further review LangCom decides we must move to Incubator, we are open to it, but would prefer not to for the reasons explained in that discussion.)'The difference with LFN and Toki is that Interslavic was never meant to serve as the language of a community of Interslavic speakers in the first place. My ambition for an Interslavic Wikipedia is that it will serve as an additional source of information for those who don't have access to it in their own language. That's why visibility is important, and from that point of view, the Incubator is still a small step forward compared to a place that few people even know about. Besides, there is more activity in the Incubator than in our old wiki at the moment. That activity is likely to increase even further after an
interview I gave about our new Incubator project a few days ago; before that, neither our old wiki nor the Incubator have ever been actively promoted within our groups.
The only real problem is the absence of a transliteration engine in the Incubator. That won't be a problem if it's only for a few months, but such a situation shouldn't linger on for too long. If LangCom would be willing to review (and if all conditions are met, approve) our project before, say, the end of the year, then we can always import the necessary tools from the old wiki once
isv.wikipedia.org has been created. That would probably be the easiest solution, now that I think of it.
As for your second point, the experiment, you are probably right about that, although the Incubator and an external wiki have at least one thing in common, namely their relative invisibility compared to a "real" Wikipedia.