https://docs.camunda.org/manual/7.3/guides/user-guide/#tasklist-customizing-custom-scripts
describes how to add custom scripts / customizing.
We did just that (changed/added files, but no ‘grunt build’).
In a restarted “productive” dev system (7.6.4-ee) all changes made to app/tasklist/scripts/config.js (etc) are deleted.
Local DEV tomcat does not show this behaviour (tomcat restarts do not delete changes).
In the exploded directory.
Probably we will end up in this client project to clone the camunda webapps, make our changes there, then deploy the new WAR file.