Thank you for checking all this. Yes, I meant 7th and 9th.

Looking at cash flights, when my outbound is Economy Basic, only one flight is offered for the inbound.
But when my outbound is Economy Plus, six flights are offered for the inbound (including Vueling).

For a return flight redemption, it's strange that ba.com will not show me anything outbound as it has no inbounds to offer.
Whereas if I just search one-way, it is happy to show the lightly-loaded Fri flights as redemptions.