Thanks. The only thing I can see is that where I have
templates/web.ratelimited.template.yml
you have
templates/web.ratelimited-whitelist.template.yml
Just possibly there is a syntax error in that file? It would be, I think, at
/var/discourse/templates/web.ratelimited-whitelist.template.yml
Although there could equally be a syntax error in any of the other templates mentioned.