The biggest risk I see is dependency on 2 incomes for sustaining the mortgage/ loan. If one of you loses the job for even a few years (not improbable for anyone as things develop) then you will have to talk to the bank.
We are in a similar situation, on our roof / under tiles exists asbestos but there is no risk as long as you don’t touch it. As long as roof it’s not leaking I am not considering to replace it, it just doesn’t make sense. PV installation again doesn’t make sense when you calculate ROI long term vs. investing that money. (Btw, there is a new option now, to use PV tiles directly - technology that is new and might be more rational in the future instead of separately doing roof then PV.) Old but functional kitchen and bathroom should probably be done after core energy related items.
Someone told me, that as long as a system works, don’t touch it 
What about heating and electricity? Are these systems ok?