Not sure if I'm following and I don't have much FARR context in my head, but If you mean something like:
1. User takes some action which leads to a plugin getting FARR to display some HTML (generated by the plugin say)
2. User clicks on a link or button in the HTML
3. The plugin executes some code in response
Then IIUC the answer is "yes".
An example of this type of situation is in the CommandPromptHere plugin
Look in the file named callbacks/onSetStrValue.js for the following code path:
buildConfigHTML generates HTML which is displayed by FARR.
Within that generated HTML is a FORM element with an action that begins with "farr://pscommand". When a user submits the associated form, the plugin gets called by FARR's pscommand mechanism. Specifically, the plugin handles this request via onSetStrValue in callbacks/onSetStrValue.js:
Does that help at all?