Custom control information files

Hey TC community!

Just wondering if anyone has had any luck with this feature in TestComplete, or has developed a plugin to support custom controls (Tools > Options > Engines > Custom Controls).

What do these XML files look like (elements, etc.)?

What is involved in developing a plugin to support custom controls?

The documentation mentions plugins can be developed but no information regarding what that entails.

https://support.smartbear.com/testcomplete/docs/reference/options/engines/custom-controls.html

Our application under test is large, complex and has a lot of custom controls which TC fails to recognize 50% of the time; performed actions usually fall back on basic coordinate clicks which are less than accurate in an application that needs high-accuracy clicks and keystrokes.

We've also tried adding the control classes themselves to the Object Mapping editor in  the project's properties, but it did not seem to add any functionality when scripting or when recording KWTs.

Any help would be greatly appreciated.

Thank you,

Joel