To my knowledge, SynEdit is an abandoned component. However due to mostly the Laz Team's efforts, it's been ported and modified to work with Lazarus.

I recommend that if you have an error or a noticeable bug, report it through the freepascal.org website. They have a whole system that they are dedicated to working on and knocking off issues one-after-the-other on a near daily basis. But if it's not in there.... you know what good that does the end product, right?