Sync from Campaigns to CRM

I have the new sync integration model set up.

pushing data from CRM to campaigns works well & nearly instant, all good here:

- I'd typically see a new record in Zoho Campaigns 1-2 minutes after it was added to Zoho CRM module
- CRM record's custom fields are written in Zoho Campaigns list contact's custom fields

I struggle to understand how the sync works the opposite way though: from Zoho Campaigns to Zoho CRM. there are several use cases for this, a couple of examples:

- when a marketing email recipient clicks on "manage preferences" and unsubscribes from a topic

- when I manually update contact's details in Zoho Campaigns interface

what is the mechanism the sync "uploads" data to CRM? do I need to create a separate workflow in Zoho Campaigns for this?

there is a Push Data to Zoho CRM doc page and this older community post but I wonder any of this is relevant or outdated with the new sync integration? furthermore I do not want activity based to sync such as on email click or open. the two systems should always be in sync.

also this doc page says:

If you want a Campaigns field to be displayed in Zoho CRM, all you have to is to add that particular field in the corresponding module, so that it will be displayed in your CRM account as well.

... this is almost exactly what I need but can't get it working

basically I want the Campaigns' contacts to be always in sync with Zoho CRM module (i. e. contacts, leads) and the sync should be both ways. how to set this up?