Try to match the stain, and restain it.

If I restrain it as is, there will be 2 colors- weathered grey and natural cedar.

Yikes ! What were they thinking? Can you find a small area and test stain? Try only doing the ones where the stain was removed ? It would probably be a bit painstaking but might be your best option.

People in my neighborhood are now using solid color stains on their weathered shake - and it looks great. It will last without the need for ongoing maintenance for decades, too. If worst comes to worst, it's not a terrible outcome.

One went sagey green, one went deep gray, one went with a smokey blue. They all look good. The shake provides great texture - but the solid color stain has a painted look that makes for a modern, fresh, consistent appearance.