In my opinion the translation of “Reusable BlockBlock Block is the abstract term used to describe units of markup that, composed together, form the content or layout of a webpage using the WordPress editor. The idea combines concepts of what in the past may have achieved with shortcodes, custom HTML, and embed discovery into a single consistent API and user experience.” is wrong. It comes out at least strangely, for example: “Reusable Block scheduled” is translated as: “Zapisany blok został zaplanowany”.
My suggestion: “Blok podręczny” or “Blok wielokrotnego użytku”.