What a great read. Please keep the updates coming.
I have an alternative solution to the locking padlock symbol on the touch screen. You can install a digital dash from the L322 Range Rover 2010-212, same electronic systems. The differentials are displayed right in front of you, with the lock symbols.
It's an easy fit, some trimming is required behind the cluster because the new cluster is slightly wider, a fan is also recommended (just connects to the existing loom). It will also need your vin & immobiliser code programmed, but anyone with a basic IC programmer will be able to do it. Then using the IID Tool you choose the display type, supercharged, petrol, diesel.
My cluster has been in place for over 2 years without any issue, in fact it really modernises the interior.
I'm in the process of installing a rear locking diff, the ECU is already in place but I need a differential! FYI all the wiring was already in place on my 2010MY apart from the chassis plug to diff loom.