The disc is a regular Australian one (IFPI 65xx instead of 94xx), I would be highly surprised if it only supported English and Arabic of all languages. Jackal is right about PS2 covers being a mess, genuine Australian releases can either have their own covers and ratings or simply reuse unaltered European covers (with the ELSPA/PEGI/BBFC/USK ratings intact), usually the latter group have an Australian rating sticker on the cover hiding the original rating. Cover swaps are all too common as well, especially when stores hide the discs and manuals behind the counter and only leave the empty case on the shelf, things are guaranteed to get mixed up.
ack2121: The Sony DADC A0900555555-B511 label side ringcode is on all wannabe-dual-layer* PAL PS2 DVD5s with the exception of very few, it's just that most of them cannot be seen under the label (which is why documentation of the label side rings is mainly limited to Platinum releases). I have come across exactly one game out of 800+ which has had a non-DADC label side ringcode, it was Tony Hawk's Pro Skater 4, which came with a Sony Music Entertainment Australia "DVD5 BLANK" ringcode (which itself resembles an NTSC ringcode). Other PAL titles such as High School Musical 3 and the PBPX demos would most likely have an NTSC style label side ringcode but it cannot be seen.
*Most regular DVD5s (and all CDs) only have one visible layer however, so looking through the label side will simply show a reverse image of the label side ringcode on those discs. I guess it's just up to what equipment manufactured the disc at the time, as even otherwise identical discs may or may not have the blank layer. There's a chance that UMDs may also have the same thing (not sure about Blu-Ray).