This looks like a useful module, especially with support for different CAPTCHA services like CapMonster, XEvil, and Anti-Captcha. One improvement I'd suggest is adding a dedicated integration example that shows the complete workflow: retrieving the site key and page URL, requesting a solution, checking the returned token, and passing it to the appropriate response field.
It would also be helpful to include a configurable retry mechanism with a maximum number of attempts and proper error handling for cases like ERROR_TOKEN_EXPIRED. This would make troubleshooting much easier and help new BAS users integrate the module without having to figure out each step separately.