The Text Editor no longer has bracket matching for parentheses (with bold highlighting), which is vital for Scheme/Lisp files, and text files in general. This used to be available before (pre-4.9), and is still available for the C/C++ editor. Looks like this functionality was broken by the recent switch to KSyntaxHighlighting.
I've attached a sample Scheme file (test.scm) for convenience. Simply place the cursor on one of the parentheses in the file, and a matching parenthesis is not highlighted anymore.