How to check trigger action working for a table? How do I know its DISABLED/ENABLED?

Is there any query to check this?

If you cannot just see the effect of the database trigger (it will be doing something, assigning field value, updating additional data, performing validation, etc.) you can use 4GL Client logging:

LOG-MANAGER:LOGFILE-NAME = "c:\temp\client.log".
LOG-MANAGER:LOG-ENTRY-TYPES = "4gltrace:5,4glmessages".
LOG-MANAGER:CLEAR-LOG ().

/* this will execute the schema create trigger */
CREATE Customer.

UNDO.

This will show that it's returning from the DB trigger in the logfile:

[22/01/17@11:49:42.013+0100] P-158784 T-160248 3 4GL 4GLTRACE       Return from Main Block "Customer" [sports2000trgs/crcust.p]

So it must have been executed.