It is sometimes difficult to translate legalese from one regulatory environment to another, despite both using English.
In terms of interpreting LASORS, I suggest to you Jecuk that an Australian aircraft rating is not valid if the underlying license is out of currency due to the AFR requirement. This is because, in Australia, you could not exercise the privileges of your rating if you had no AFR-currency on your license. If you cannot exercise the privileges of a rating in your home country, you cannot claim it is valid in another country.
So the question is: within the past five years, could you at any time have legally conducted a flight in Australia in a SEP (Land) aeroplane, using your CASA PPL? (Ignoring the requirement for a CASA medical.) If yes, then you're in the clear. If no...
This is just one interpretation. But it's the opinion I have offered in the past, on LASORS C1.3 and similar sections, as a UK examiner myself.