We invite everyone to submit issues on the forum if you find one. You can also start by taking up a discussion on the forums to verify your thoughts on the issue.
Some resources to get started with DataCleaner extension development:
DataCleaner builds on top of Apache MetaModel for it's connectivity layer. In fact, many of the core developers of DataCleaner are also core developers on Apache MetaModel.
The reference documentation of DataCleaner contains several chapters on important topics for developers such as: