Unconventional way of learning a new programming language
hackernoon.com
hackernoon.com
Not in my experience. When I learn a new language by implementing a project in it, I do not consider the job done unless I have written idiomatic code in the new language and really understood every piece of code I took from Stackoverflow.
Not saying that contributing to open source projects for learning a new language isn't a good idea. Free code review in exchange for your contribution to the project is a win-win.
Personal projects in languages that I'm already familiar with are the places that I allow myself some sloppiness.
It's probably best to ignore any projects that have not had any recent contributions at this stage because the maintainer might have lost interest so you won't get any feedback about your contributions.