When "was" means "used to be": How do I explain it?

I'm working with a colleague who speaks excellent but non-Native English, and I'm having trouble explaining something about the present and past tenses. We are trying to write something together.

I want to tell the reader "Alice is a member of organization Q" and "It usually takes Roy three hours to bake a cake."

My colleague wants to say "Alice was a member of organization Q" and I'm not sure what they want to say about Roy, but they don't like the present tense.

I'm having trouble explaining that the switch to the past tense implies "Alice was a member of organization Q but isn't any more" and "It took Roy three hours to bake cakes" while implying that it takes a different amount of time now.

Per the facts we want to convey, we have no reason to think Alice quit organization Q since we last checked with her a few days ago. My colleague thinks it's misleading to say "is" when it is humanly possible for Alice to have quit. I've pointed to other mostly-past-tense articles that use the present tense in this way.

Can anyone explain this better than I can and allay my colleague's concerns about misleading our readers?