“EEID_FINDBAR_INCREMENTAL” is not a ID, but a string, the name of that command.

The ID is 4571

See EmEditor Help – Command Reference – Search category

Incremental Search (Find toolbar) command
Toggles the Incremental Search button on the Find toolbar.
Toggles the Incremental Search button on the Find toolbar. When Incremental Search is activated,
EmEditor will search and highlight results as the user types.

How to Run
Default Menu: None
All Commands: Search > Find Toolbar > Incremental Search
Toolbar: None
Status Bar: None
Default Shortcut Key: None
Plug-in Command ID

Also take a look in the help for EmEditor Macro Reference – Editor Object > QueryStatusByID Method

Retrieves the current status of the specified command, whether it is enabled and checked.
nStatus = editor.QueryStatusByID( nID );

Specifies an integer indicating the Command ID to execute.
See the Command Reference for the list of available commands.

Return Values
Returns a combination of the following values.
eeStatusEnabled The command is enabled.
eeStatusLatched The command is checked.