The extension uses https://en.wikipedia.org/wiki/Template:Reviewednote-NPF
E.g.
{{subst:Template:Reviewednote-NPF|Page title|Username|This message contains an = sign}}
Will render {{{3}}}
Instead we need to use:
{{subst:Template:Reviewednote-NPF|1=Page title|2=Username|3=This message contains an = sign}}