When I clicked on the title, I expected to learn about how to create a Linux GUI. This article did not, in any way, shape or form, teach me anything about how to create a Linux GUI. It introduces a tool which solves a problem I'm not sure I'm having, related to packaging (why would I care, it's the distributor's job anyway, no one using Linux should ever have to download an installer manually, ever)
SEO is not about promisig something, making them click, and then giving people something completely different. It's about targeting the needs of a group that has a particular pain, and addressing them well.
I like that the project supports AppImage. I don't suppose fman supports displaying AppImage icons? I've been keeping my eye out for any filemanager that does.
I already have a few other articles targeting other key words, and I feel the unique contribution of this one (and the latest version of fbs, which this one aims to spread the word about) is a much better solution for ... Linux GUI programming. But I'll keep in mind what you said. I'm still pretty new to SEO.