I’m not sure what you’re experience is with it, but that fundamentally shouldn’t work. Plenty of other people run into problems like this one by doing what you’re suggesting.
Once you have a copy of the plugin in your project, it becomes a project plugin. And Engine plugins can’t depend on project plugins. (and you should start getting build errors like those in the linked post).
Maybe you’ve only modified plugins that don’t have Engine dependencies. There are plenty of those.