Hmm ... maybe we need to answer another question first -- what do we think the term "Black Court Elder" means?
I'm seeing it as a stage of maturity -- an Elder is to a Master Vampire what a Master Vampire is to a normal Blampire -- rather than, or as well as, a designation of raw power or a political term. It means a Blampire whose vampire powers have (due to immense age) hit about the upper limit those powers go to - whether that vamp has spellcasting, or massive political power, or not.
So Mavra's at something like -27 Refresh - but she's not, in my view, an Elder because she's still maybe a century or two old and she's still "only" got Supernatural Toughness and Strength, etc. Even if she had like ten Refinements on top -- though she'd be more powerful than many Elders -- she still wouldn't be one.
So when I made a "low end" Elder, I made one with just the supercharged vampire powers, not the spellcasting etc. I'm not arguing that this -26 Refresh dude is "what all Elders look like" -- this is meant to be the "basic Elder" which you can then give spellcasting, etc. to.
If you think Elder is a measure of raw power instead, then it all works different. (But that would leave you with, probably, no non-spellcasting Elders, which I don't find desirable...)