Need to make custom UI inside plugin settings frame

[backskin]

Hello! Does anybody know a clever way to make a customized UI inside this plugin settings window (at APIs/Design tab)? I am already familiar with a schema settings in schemas/schema-form.json, but my task requires more manageable interface.
I need to add some custom logic like adding user list of policies with multiple parameters inside one element; searching by excerpt on this list of complicated elements; adding switches and custom buttons with its logic inside list's element.
An example is on the screenshot below