I definitely would appreciate customizing rules in standalone mode. I attempted installing SonarQube and going the "connected mode" route. However, I had difficulty getting the SonarQube service started and I am not a Java guy.
Some of the rules are more annoying than helpful. I have no idea what "naming conventions" DelphiLint is expecting. One convention seems to be that unit names must be PascalCase. Particularly for legacy projects, there is no benefit. Yes, a consistent naming convention is very helpful. Does anyone care that all of our form units follow formMain.pas rather than FormMain.pas?
I almost want to create an issue for the rule "split this 128 characters long line (which is greater than 120 authorized)". Authorized by who, or what? Certainly not by me, my employer, or anything that I've configured in Delphi.
Others are personal preferences. "Delphi style guides" may advise against using () when calling a routine without arguments. But I prefer to have them. They do no harm and I think they improve code read-ability.
Those are just a couple examples where the ability to customize the rules, even in standalone mode, would be appreciated.