This query lists tables that are not added to any ER diagram:
SELECT d.title as [database], t.[schema], t.[name] as table_name
FROM [dbo].[tables] t
inner join [dbo].[databases] d
on t.database_id = d.database_id
where t.table_id not in (select table_id from [dbo].[erd_nodes])
and t.object_type in ('TABLE') -- add 'VIEWS' for views
order by d.title, t.[schema], t.[name]
This query returns tables assigned to modules but not added to an ER diagram:
SELECT d.title as [database],
m.title as [module_name],
t.[schema],
t.[name] as table_name
FROM [dbo].[tables] t
inner join [dbo].[tables_modules] tm
on t.table_id = tm.table_id
inner join [dbo].modules m
on m.module_id = tm.module_id
inner join [dbo].[databases] d
on t.database_id = d.database_id
where t.table_id not in (select table_id
from [dbo].[erd_nodes] en
where en.module_id = tm.module_id)
and t.object_type in ('TABLE')
order by d.title, m.title, t.[schema], t.[name]