I read it as you wrote it.

No you didn't. You can't say "quite limited to" and use it as meaning
"limited to". Your interpretation is actually gramatically incorrect. It is
understandable why you made the mistake, however.

"permitted development rights to the front elevation are quite limited"

Perhaps, so as not to mislead, it would be better stated; - The front
elevation,with minor exceptions for porches, may not be changed without
planning permission.

But that is not what I said. Indeed it is not true. Porches are not the only
exception. There are others.

Christian.