RSyntaxTextArea and RSTALanguageSupport have a 2.5.6 release on GitHub and Maven! These releases fix up some issues found in the recent 2.5.4 releases. They are compatible with the 2.5.4 releases of AutoComplete, RSTAUI and SpellChecker. RSyntaxTextArea in particular is worth upgrading if your application runs on OS X, because it brings a big performance improvement with rendering tokens with background colors specified.
Moving forward, I hope to more strictly follow semantic versioning, but I give no promises. But the goal is to no longer tie myself to synchronous releases of all of the RSTA sister projects at once. All of 2.5.x, for example, should be obviously compatible with one another, and indeed, 2.x should as well. We’ll see how that goes moving forward.