you can try this first :Consumer Council and Consulate of your maid, at least refund you the Philippine Insurance they charge, it is not transferable to the new maid, unlike the HK insurance.
https://www.consumer.org.hk/ws_chi/choice/474/complaint-maid.html
If the medical report is false, saying she is in good health condition when she is not, then it is not a civil case, it is a criminal case...ie. the doctor/lab giving the false health report has legal responsibility.
No one can shoot from normal to 200 within a few months!!
Get medical report from the doctor or hospital with 200 blood pressure. She is in no health condition to work. The agent usu support the maid in court, 90% will do that. They will both say in court that you forced her to sign the resignation cause they will share the one month notice in lieu! Get evidence that the agent and the maid are cheating about her health condition. Call the immigration department to see what other documents you need to support your case.
Good luck!