How can I postpone my biometric appointment and return to my country without jeopardizing my EB-5 process?

Yes, the biometrics can be postponed; send a letter and advise the time period for rescheduling that is convenient. If you have the conditional residence but I-829 pending, this should not affect this.

To apply for and receive a reentry permit, you will need to complete biometrics prior to leaving the U.S.

Very dangerous! If there is a good reason, you can request, but if you miss it they are issuing denials. Best to get your biometrics before you leave. And best to return within 1 year, at the latest, and make sure you file the U.S. tax returns and that you maintain your home here, and have a good reason to be abroad.

You can return to your home country and request to reschedule the biometrics one time. You should definitely make all efforts to come to the biometrics appointment after you schedule it. The USCIS may deny the I-131 application if you try to reschedule the biometrics more than once.

Yes, you can postpone the biometrics. The rescheduling timeline depends on location; in Los Angeles it seems 4+ months.

You can return to your country after submitting the reentry permit application while you are in the United States. The ASC appointment notice contains instructions about how to reschedule the biometrics appointment. It would be best to return to the United States within two or three months to complete the appointment.

The USCIS will allow a few weeks maximum to postpone your biometrics.