That advisory would probably be more helpful if it described what the actual issue is. (I’m thinking maybe some content got lost when the Update at the top was added?)

Yes and it is very unclear to me what are actually the risks...

I am unfamiliar with "coldcard" but can hackers find out which wallet is used for which account? or maybe it can be inferred by analysing the transaction (if any)?

If the hackers do not know which accounts to attack first there is probably no need to panic right now.