The combat management systems (CMS) controls the ship's weapons and sensors systems. The Australian T-26 will apparently have a Saab 9LV CMS which will handle most of the weapons and sensors, but will also have part of an Aegis system tacked on the side with an Australian display just to handle SM2 or SM6 long range missiles.
The T-26 bid for Canada will apparently have a CMS330 system which can handle ESSM and Sea Ceptor. I've seen no mention anywhere of SM2 or SM6 missiles for them. CMS330 was also part of the upgrade to the existing Halifax frigates, so that offers good compatibility between the Canadian version of the T-26 and the existing fleet as the two will need to operate side by side for many years as the new ships are phased in. Sea Ceptor capability was added for New Zealand when they had their frigates modernised in Canada with the CMS330, but I don't know if those missiles will be used by Canada. The bids are already in for the Canadian contract, so it would be pretty difficult to change any of that at this time.
The Type 31 will apparently have Sea Ceptor missiles, so there's not any reason to have an Aegis component.
The article you linked said the US will be using a COMBATSS-21 CMS, which is apparently some sort of Aegis related system. I understand there has been some controversy in the US over this choice, as it is believed this will push up costs beyond what was considered desirable for frigates. I would not be surprised if what we were seeing here was someone trying to justify the cost on the basis that other countries were potentially interested in it as well.
The Australian T-26 will apparently have a Saab 9LV CMS which will handle most of the weapons and sensors, but will also have part of an Aegis system tacked on the side with an Australian display just to handle SM2 or SM6 long range missiles.
Hence the changes to the Canadian frigate program after the last election. Originally, the combat systems were to be selected separately from the ship itself and then there would be a third contract awarded for systems integration. This was changed to making the ship designer responsible for the whole project with the intention of buying a, nominally at least, "off the shelf" package.
No project of this nature is ever completely off the shelf, but the intention at least is to minimise both the cost and delays of system integration.
It's already been done in their new destroyers so they've already paid for the disasters and overruns. Although there's a whole load of ASW requirements in the Hunters that wasn't there before so plenty of scope for ramping up the contract value.
Their original bid had some deficiencies or errors and they were allowed to correct and re-submit it. The same is true for the other vendors. This stage of the precess was planned for so there is no significance to it other than that the bid submission process is now closed and final evaluation is taking place.