Hi Christophe, Thanks for the feedback, and sorry for the late response. This is definitely not a one-size-fits all solution. In terms of colors, I have been thinking lately perhaps there is a more accessible representation of this that isn't so color-based. Contrast can be an issue for people to digest information, and I think that this doesn't offer the greatest contrast.
However, I do think the sheet has its benefits. For our purposes it has been a great digital version of something like an affinity diagram for some complex projects. I of course know there are several digital boards for creating affinity diagrams, but I think this is a good substitute if something like Google Sheets is the handiest tool available at the time.
What I also like about it is that the Rainbow Sheet template comes with a few other tabs where you can track different success metrics.