Hello, thank you for your question.
As stated in the FAQ post:
Third party analyzers are not executed in SonarLint
Some issues may be reported in SonarQube by a plugin leveraging a third party analyzer (PMD, Checkstyle, ESLint, PyLint, …). SonarLint will only run rules from SonarSource analyzers including custom rules extending SonarSource analyzers . Third party analyzers usually have their own IDE integration, so we have no plan to run them in SonarLint.
So even with the sonarLintSupported flag, your custom plugin will only be executed by SonarLint if it extends one of the official analyzers, and only in connected mode.