So -- please point me to a FAQ if there is one -- exactly what is "internal skill"? Or "internal power"? Maybe there's a coherent, consensus answer to that, but I expect what I'll hear is more like the blind men describing the elephant.
I don't know of any accredited "FAQ", but Koichi Tohei's book "This Is Aikido
, With Mind and Body Coordinated" was written under the auspices of Hombu Dojo and so Tohei's comments and particularly his (and his students) demonstrations would qualify as a Rosetta Stone from which to derive the basis of something like a FAQ. In other words, Tohei's "Ki Tests" and demonstrations in that book were done at the time when he was still the chief instructor and the book was approved by Ueshiba M.... so the physical demonstrations of "ki" (aka "internal strength", etc.) are pretty concrete starting points. Of course a lot of people are going to offer opinions of what they think ki is, but my comment would be that before someone has the right to claim they know what ki is, they should be able to demonstrate all those simple examples in Tohei's book.
Based on conversations and my own experiences with a few of the regual AikiWeb posters who I consider credible about at least some aspects of internal strength, I don't think that baseline of "be able to do Tohei's ki tests" would be questioned by any of them. So maybe that's a good starting point? I don't know if Tohei ever had a baby, so I'll have to demur on that point of the discussion.