Email..."Any trips taken after your initial purchase will not appear on your account. Rest assured, you will be covered for any other trips during your yearly period as outlined in your certificate."
Which I read as the cover maybe valid for other trips/airlines, not just Ryanair.
Ryanair help page...."If you have purchased an annual multi-trip insurance policy, the policy will take effect from the moment you purchase your flight and policy for a period of one year. Your multi-trip insurance policy offers you insurance protection in line with your Ryanair flight timings taken during that year of cover."
Which I read as Ryanair only flights are covered.
I have decided to purchase cover elsewhere as I have no confidence I am covered with my new airline (or any others within the 12 month period).
I will never be buying insurance linked to an airline again, too much to worry about, for what should be peace of mind.