Why do I continue to use Rudolf Steiner's terminology (e.g. Luciferic, Ahrimanic, Sorathic) despite that I have modified the meanings?

The above question was asked me the other day; and it is a good question. 

After some consideration, I realized that the answer is that I use Steiner's names to acknowledge the substantial debt and origin of the concepts; and then I develop the idea.

I do not attempt to conceal the development - indeed I discuss it explicitly; but typically only when I first start making changes, and not at every subsequent usage (or, only by providing links). 

This seems wrong, lacking in rigour, to those who is operating under the conventions of scholarship in the humanities; where the ideal is to preserve without alteration the original meanings attached to terminology. 

But I am (or was) a scientist, and Rudolf Steiner regarded Anthroposophy as a "Spiritual Science".

In science, this is how concepts (theories, hypotheses, even specific entities) are often developed and used. Names are retained, but their meaning develops. 

Thus concepts/entities such as light, gene, electron, natural selection - all mean something different to later scientists than to their originators; and this is taken for granted because meaning is established by current usage, not by retrospective scholarship.

Science is about developing knowledge, so it is expected that definitions, theories, practices will develop - change their meanings.

So it is quite natural and unremarkable for me to get ideas from Steiner, and to modify them in this scientific spirit; just as it is natural for humanities-orientated scholars to define a new term, every time they modify an existing definition or a theory. 

This also fits with my attitude to Steiner's work as a whole. I disagree with most of what he said and regard it as wrong, and I regard Anthroposophists (and the Anthroposophical Society) as - usually - fundamentally misguided... 

Nonetheless, I regard Steiner as one of a handful of the most important thinkers of recent centuries; and have spent a great deal of time reading and thinking about his work (and his life). 

It seems strange to read and write so much about Steiner while regarding him as mostly-wrong; but, again, this is not unusual in science - where one may base a great deal of research on a particular paper (a finding, an hypothesis), or part of a paper, by a particular scientist - without having any concern with anything else he did. 

This, then, is what I do and have-been doing. It's useful to get such matters clear in the mind.