Pre-orders are now up on Amazon Australia, as Australian stock.

The dates are a bit weird though, as the dates on the product page appear to be different to the arrival dates on the checkout page (like the Shattered Glass Ultra Magnus says that it will be released September 15th, but will arrive at your address between August 4th to 8th... which means time travel if true).
Considering how late the dates are on Amazon America compared to their official release dates from Hasbro, maybe see the dates as the latest they will be released by, and that they are most likely released a month or two before that.

Shattered Glass
LDR Ultra Magnus - $104 SEP 15th

Legacy
LDR Blitzwing - $97 AUG 15th
VOY Gen2 Jhiaxus - $53 AUG 15th
DLX Knock Out - $37 AUG 15th
DLX Wild Rider - $37 AUG 15th
DLX Tarantulas - $37 AUG 15th
DLX Elita-1 - $37 AUG 15th

Re-release Siege Soundwave without battle damage paint (jet version, not Netflix tape player) (probably in Legacy toyline) - not listed.
CMDR Motormaster - not listed, as it is being released in June for a toy sale first, before being released later in the year at other retailers.