In my experience, with 20 teams and 10 ScrumMasters, things can get misaligned. ScrumMasters and teams diverge using their own processes, multiple DoDs, even Backlogs, development processes. The ScrumMasters disagree on common processes and nothing aligns.
I believe that one person is required to ensure the teams align to a single process, this person will "coach" the Scrummasters on what to do.
I'm curious, what is their position in the organisation? Should everything by done via coaching or is there is directing? Is there a practical other solution?