Those are almost assuredly awful projects when you are interested in learning a new language. Obscure software likely is laden with domain-specific knowledge t

Those are almost assuredly awful projects when you are interested in learning a new language. Obscure software likely is laden with domain-specific knowledge that you don't have (otherwise you'd likely know about the commercial software). Known commercial applications with no open source equivalent are likely that way because it is difficult to build a replacement. When learning a new language, you're almost always better off picking a simple problem so you can focus on the ergonomics of the language. Trying to learn a problem domain and a programming language at the same time is really hard, and is a common reason why startups picking niche programming languages run into trouble