I just released an early version of a plugin which will unify code block syntax highlighting between edit and preview modes. It has support for a few different syntax highlighting themes out of the box and support for importing your own themes.
I plan on submitting this to the official plugin repository in the near future but if anyone wants to test and provide feedback, you can check it out here: Release 0.0.2 · nothingislost/obsidian-codemirror-options · GitHub
