Yes it does, but I believe there's still more to it!
I think the connections to your existing stats are made behind the FCU, as I can't see the pair of three core and earth cables, that should join to them.
If you do choose to show us behind there, be careful, as even with the switch turned off, there will be a live connection on the supply side of the switch.
I can't believe that the sales people at Wiser said it was a 10 min install and I could do it without needing any help.
I wouldn't be too harsh on the Wiser; many installs use a 'universal' back plate, which would mean a straight and easy swap.
Your install is definitely one of the more interesting ones!
If you wish to experiment, you could make these connections (with power isolated) to the Wiser backplate...
Keep the existing wires in place, just add the new ones into the terminals with them.
Keep your existing thermostats turned OFF.
Beware, this would just be a temporary proof of concept; your existing thermostats would not be decommissioned.