Hi Matanic having been involved with SSiC from the start and the many stalled initiatives surrounding the revival of Cornish in this century, I can honestly say that abandoning the concept of 'forms' and the notion of orthography is the best way forward.
There is, of course, a place for linguistic research and historical accuracy but it acts as a drag on meaningful revival in my opinion. The best form to my ears is that which my son’s godchildren (4 and 5) speak. When teaching we are pulled towards what young people ‘like’ and use in speech. For Cornish this leads to happy engagement in alliteration and a preference for Breton and Welsh loan words over English (although this could parental/teacher prejudice coming through).
For us SSiC is perfect because it allows a learner to dodge the arguments regarding what is ‘correct’ and ‘authentic’ in terms of form. Once a learner becomes proficient at understanding and speaking they can take their Cornish in whatever direction they like. I suppose if we have to pinned down on this subject we are putting prosody and language patterns to the fore and leaving orthography, in particular, for another time.