Can endoscopic carpal tunnel release be safely and effectively done in cts with bifid median nerve (or must open method be done with bifid)?

Yes. The endoscopic carpal tunnel surgery can absolutely be performed safely on patients with a bifid median nerve but that depends on the surgeons comfort level with the particular technique they use and with your particular condition.
It can be but. A careful exploration of the median nerve be done in carpal tunnel and extensive pre operative assessment of median nerve morphology and function should be done prier to endoscopic surgery to treat cts bifid median nerve is also accompanied by persistent median artery as well.Some surgeons feel more comfortable using the open method. Ask your surgeon what his/her recommendations are based on studi.
Likely safe. Although not a surgeon, my hand specialty colleagues seem very comfortable with the endoscopic approaches, and the outcomes seem uniformly terrific with uncomplicated recoveries. Discuss fully with your hand surgeon, and you may be very reassured.