Currently, we don't have plans for implementing a PL/SQL taggers. If other customers have similar requests, we will consider it in the future improvement of the control. However, you can implement your own language by implementing a custom tagger. A sample approach is demonstrated in the following help article: https://docs.telerik.com/devtools/winforms/controls/syntax-editor/features/taggers/custom-language
I would recommend you to download the Telerik source code from your account a have a look at the default implementation of the SqlTagger. You can use it as a starting point of the implementation you need.
I hope this information helps. If you need any further assistance please don't hesitate to contact me.
Regards,
Dess | Tech Support Engineer, Sr.
Progress Telerik