In Java Swing a JTextPane can be switched to editable, but then needs some editing environment around to be able to e.g. set font/sizes/... - this is e.g. exactly what the SimpleHtmlEditor does - it is internally build based on an editable JTextPane. In Java FX there is not direct JTextPane equivalent at all, but only some text area (all one font) and a WebView for HTML.
...so the editing of text is available as TEXTAREA in both environments and as SIMPLEHTMLEDITOR also in both environments (in Swing you have to in addition download SimpleHtmlEditor component).