So under which appeal grounds would this fall?
A “procedural impropriety” means a failure by an enforcement authority to observe any requirement imposed on it by—
(a)the TMA 2004,
(b)the 2022 General Regulations, or
(c)these Regulations,
in relation to the imposition or recovery of a penalty charge or other sum.
If publishing information on a website or even linking to a website - absent statements in a notice itself - was a PI then the vast majority of TPT appeals would succeed and similarly ETA because the Tribunals' key website info is flawed. But it's not their duty, it's the authority's.
Now, if a person acted upon and within their notice but, for example, payment was not accepted by the council then this would be a different matter IMO.
Reference was made to 'cases' which apparently support the PI claim. Could I suggest that the best two or three are referenced for the OP's purposes.