Yes, JAL a good option for people who want certainty and are prepared to pay $3500/pax plus the quarantine fees. If home quarantine comes to reality there will be at an instance an extra 18,000 seats a week put into Sydney, and I suspect fares will be considerably lower than that.
FJ - provides certainty of a secure seat if home quarantine comes into reality. But if it doesn't, and the caps remain, FJ will almost certainly be cancelled (they've been selling these sort of fares on and off at different times, at one point during April they were selling fares in Aug/Sep for $700 SIN-MEL, that didn't go ahead). . I still don't see a compelling case for booking now vs waiting for those 18,000 seats to open up.