The regional center and the project operator are prohibited by USCIS from offering any kind of guaranty, since Congress created the EB-5 program based on the investor investing money, not lending it with a guaranty of repayment. Investment implies that the funds are placed at risk of partial or complete loss. Therefore, USCIS takes the position that if the regional center or the project operator offers a guaranty to the EB-5 investor, then the funds are not properly at risk as an investment, and, hence, do not qualify under the EB-5 program.
However, I would like to point out that the EB-5 investor can invest in an EB-5 project entity that, in turn, loans money to a project developer. The EB-5 project entity can require that the project developer/borrower guaranty repayment of the loan and provide collateral and security for the loan. The main point here is that nobody is providing a guaranty to the individual EB-5 investor, but rather to the EB-5 project entity in which the EB-5 investor invested. This is an approach that USCIS has approved in many projects.