ORDER placement for trigger in t-sql
There are 4x different RDBMS products under the Sybase name ... Adaptiver Server Enterprise (ASE), SQLAnywhere, IQ and Advantage.  The 4x products do not share a common SQL language/syntax.
The question references a link for the create trigger syntax in ASE.
The sample code in the question appears to also be for ASE.
However, from the comments we've discovered the OP is actually using the SQLAnywhere product (version 16.0.0.1915).  And while SQLAnywhere does provide some half-workable support for ASE's T-SQL dialect, it does not include a common syntax for the create trigger command.
From the comments: OP has located the documentation for SQLAnyhere's create trigger command.
Using one of the examples from that link (scroll down to find CREATE TRIGGER myTrig), and modifying OP's current trigger code to match the documentation, I'm thinking OP's looking for something like:
create trigger &quot;DBA&quot;.&quot;WKM_autoFillCL143&quot;
after insert order 4 on &quot;DBA&quot;.&quot;case_checklist&quot;
REFERENCING NEW AS inserted
FOR EACH STATEMENT
BEGIN
....

NOTES:

I work primarily on ASE, and my SQLAnywhere experience is rather limited, so OP may need to tweak the above to work correctly in SQLAnywhere; also ...
OP should review the various options available via SQLAnywhere's create trigger command (eg, should the trigger fire before or after the insert?)
OP will need to review the rest of the current (ASE/T-SQL) trigger code to see which parts can be used 'as is' in SQLAnywhere and which parts will need to be rewritten to match SQLAnywhere's syntax
OP will also want to verify SQLAnywhere's support for quoted identifiers (ie, does the current use of double-quoted identifiers meet SQLAnywhere's syntax?)