CB Auto Actions Tutorial #04.
Creating and maintaining a CB Integer Sum field using a field action or a query action.

www.youtube.com/playlist?list=PLp0puRITgC7McQcw0Sli1qfSUQGwmflzi

Resources used:

CB 2.0.4
CB Auto Actions 6.1.1+

Logic behind conditional tab:

[var3_cb_score1][var3_cb_score2] Not Equal To [var1_cb_score1][var1_cb_score2]

e.g., if score 1 is updated from 1 to 2 and score 2 is updated from 10 to 11
then this condition evaluates to:

110 Not Equal To 211

and the auto-action will be executed

But !!! what if: score 1 is updated from 31 to 3 and score 2 from 3 to 15
then the condition becomes:

315 Not Equal To 315

WHICH IS NOT WHAT WE WANT!

So, we just add a separator character (e.g., !)

[var3_cb_score1]![var3_cb_score2] Not Equal To [var1_cb_score1]![var1_cb_score2]

and this way our previously failing condition will now evaluate to:

31!5 Not Equal To 3!15

It's just taking 2 fields and stacking them next to each other. It then compares the old fields to the new fields to see if the value changed. If it did the action triggers. If it didn't then the action is skipped. Example as follows.

Field 1 = 10
Field 2 = 11

[cb_field1][cb_field2] = 1011

The above tutorial is making sure you add a separator since we're dealing with integers and you don't want odd conflicts to happen. So we'd add a separator to my above example as follows.

[cb_field1]![cb_field2] = 10!11

Below is an example of how without a separator things can go wrong.

Old Field 1 = 11
Old Field 2 = 1
[cb_field1][cb_field2] = 111

New Field 1 = 1
New Field 2 = 11
[cb_field1][cb_field2] = 111

The new values swapped field 1 and 2. This causes the combined values to be 111. Same as the old value. So if you compare the old and new they're equal. This doesn't happen with a separator as follows.

Old Field 1 = 11
Old Field 2 = 1
[cb_field1]![cb_field2] = 11!1

New Field 1 = 1
New Field 2 = 11
[cb_field1]![cb_field2] = 1!11

Those are not the same so the action will trigger. This is really only necessary when dealing with combined integer conditions. You have to do things this was because there's no OR conditions in CB Auto Actions yet.

Was assuming when using multiple conditions (more than 1 row of conditions) in auto action there's an OR operator between each row of conditions.
Hence meaning: execute auto action when at least one of conditions provided is true. Am I right?

No, there are no OR conditions unless you do as explained above or use a REGEX condition operator then use the OR separator in your REGEXP. Conditions in CB Auto Actions are always AND.

And where can we learn about these mysterious "var1", "var2", etc.? I have been looking all over for an explanation of these. For example, why, in the original example above, do they use [var3] and [var1]? Could they have used [var9] and [var5]? Or any other of the "var" variables available?

The variables available is entirely dependent on the trigger used. They're the variables the trigger passes. CB Auto Actions has no clue what those are, but it maps them to var1-15 to allow access to them. You can review the below trigger list for an idea of what the variables are for a given trigger.

www.joomlapolis.com/documentation/279-community-builder/tutorials/18358-using-cb-triggers