Mirroring basic information between boards

I’m trying to do a really simple task that would be absolutely basic, out of the box on any other CRM, but seems impossible to do here. Posting here in the forums as “Support” has been completely useless, way below the standard you would expect for what is quite an expensive product.

So we have a board with all our company contacts in. Tens of thousands of them. We also have a “Campaign List” board, and a reference field in “Contacts”. So we can attach people to Campaigns, simple use case, we need to track correspondence with people in regard to a campaign.

So what we need is another board, where we can add some extra fields (like “RSVP’ed”) that lists contacts who can be sorted / filtered by the reference field as above. Ideally, changes made on either board should be reflected on the other.

Unfortunately, automations to copy the contacts onto a new board only seem to copy certain fields. Also the “mirror” function simply does nothing - I’ve added mirror fields in the expectation they’d sync with both boards, but they’[re completely blank and display nothing.

Like I say, really basic functions that don’t seem to work. And absolutely useless support, canned answers with zero applicability to the problems I’ve explained. Seriously, google sheets works better than this for free, and if it wasn’t for the inertia of changing everything back, I’d bin Monday tomorrow.