It looks like that via the OPNsene API you can enable/disable rules that defined on the Firewall - Filter - Automation window, but you not those that are defined under a Firewall - interface window. For example if you have rules defined under Firewall - LAN you cannot enable/disable them using the OPNsense API.
I am using the Community edition, so maybe this is possible in the business edition - but the help documentation doesn't seem to say that it is. Is this the case?
I just want to be sure before opening up a feature request for it.