You can use an editor like Audacity to halve the pitch and you’ll hear the sounds become much more like the usual Moog timbres on later records from that era. (And yes, Carlos has admitted this herself.)
The records were a team effort. The arrangements were shaped by producer Rachel Elkind, and Baroque specialist Benjamin Folkman.
I’m just as impressed by the fact that Carlos built her own mixer (difficult, but not entirely exceptional) and multitrack recorder (extremely difficult, and definitely exceptional) for the recordings.
Creatively I prefer some of the other work, especially Beauty in the Beast, which is still far ahead of its time now, and By Request, which has some outrageously clever and fun arrangements of other music. (The Elgar pastiche is genius-level and just plain hilarious.)
I think Tomita is another great example of a musician who took material and adapted it for a new medium in really interesting, innovative ways.
I have no idea how to copy some the sounds Tomita got from his Moogs, and I’m fairly sure no one else does either. Some are easy, some are “That’s really clever.” But there are more than a few that I have absolutely no clue about.
The fact that he patched up and recorded these huge flamboyant orchestral-sounding pieces note by note and line by line with such a creative range of unique and original sounds is just astounding.
On the other hand Pictures at an Exhibition is a piano solo piece. If it has a fancy "synthesized orchestration" Tomita, like others before him, developed a fairly arbitrary adaptation.
That’s the point about Tomita - there’s nothing “arbitrary” about the orchestrations. They’re an updated and exotic take created by someone who is rooted in that lush late tonal school of orchestration, but is using a completely new instrument to make original sounds.
Snowflakes Are Dancing sounds a lot more pianistic. The later Tomita albums sound more like attempts to reinvent symphonic music, with some quirky additions. He’s very consciously shaping the music like a conductor would, while painting with evocative sounds - very much not arbitrary at all.
Lots of other synth albums are technology demos, collections of cool sounds. Switched On Bach stands out because Carlos adapted Bach for the medium of the Moog synth, clearly understanding the compositions' underlying gestures, and ensured that those gestures all come through. In some cases, they come through more clearly than on the original instrumentation, especially bass lines where the synth speaks more clearly than acoustic instruments can.
Such details in another performer's hands could be distracting, messing up the relationship between foreground and background elements and drawing attention to the wrong things -- but Carlos's arrangement and performance are exquisitely balanced. This could only have been achieved by someone with a deep and sophisticated understanding of the source material, combined with incredible patience to wrestle with difficult and immature technology until the recordings were perfected.