I think you’re mixing up a couple of the limits relating to syncing. To clarify, Airtable’s pricing page says Pro Workspaces get 10 synced tables per base. A “synced table” does not refer to tables which have one or more views synced to somewhere else. A “synced table” is one that gets its data from one or more other sources. This terminology may shift if Airtable ever permits 2-way syncing.
If Table A needs to be displayed in 1,000 other bases there is nothing stopping you from doing that.
If a Base needs 12 Tables, each of which needs to pull in data from somewhere else, you have exceeded this limit by 2 tables.
It does not matter if each synced table in a base pulls data from a different source, or if any of the synced tables pull data from the same source. This limit is literal in that it is the simple count of tables in the base, not the sources.
There are effectively two types of sync sources: internal (a View/Table in another Airtable Base), and integrations/external (Google Calendar feed, Salesforce, etc.)
Pro Workspaces can have up to 7 sync integrations per Workspace. That means if you use all 7, the remaining sources you use must be from Airtable tables.
If Base A has one synced table called “Events” that pulls in data from your Outlook Calendar, your boss’s Outlook Calendar, and your Google Calendar, that’s 3/7 sync integrations used and 1/10 synced tables used.
If Base A has one synced table pulling data from Outlook, one synced table pulling data from Jira Cloud, and one synced table pulling data from Miro, that’s 3/7 sync integrations used and 3/10 synced tables used.
If Base A has an “Events” table syncs from your Outlook, Base B has a “Tickets” table in that syncs from Jira and Zendesk, that’s still 3/7 integrations used spread across 2 bases instead of 1.
As implied above, bases in Pro Workspaces can have tables which can sync from multiple sources, and as of today that limit is 3 sources per table. That’s how you can get 3 different calendars synced into one table.
Relating the above back to the examples you gave:
Whether this hits any of the above limits depends:
Is “A” a table? You can only sync 3 “things” into Table A. It does not matter if B, C, D, or E are Airtable tables, Jira tickets, etc, you’ll only get to keep 3 of those 4.
Is “A” a base? Then you’re fine since that’s 4 synced tables and the limit is 10.
Are B,C,D, and E each tables in the same base? If so you’re fine as 4 is less than 10.
Are B,C,D, and E each tables in separate bases? Airtable has no limit to prevent this.