We are fine with H1-B Visa's, but we would also need a copy of your unexpired passport with the I-94. You'd also need a social security number and have at least 2 of the 3 major credit bureaus reporting credit scores.
Unfortunately inaccurate pre-approval letters are given from time to time, there is nothing illegal about them because everything is still subject to underwriter's review. Although it is not a good business practice, which is why to prevent that I always recommend people who are in difficult situations to have an underwriter review their situation as part of the pre-approval process.
If you used the standard California Department of Real Estate sales contract then your contract is contingent upon getting an underwriting approval, unless you've already waived that contingency. So if you haven't waived or removed that contingency, then you may still be able to exit the contract without losing your earnest money deposit. It's best you discuss that with your real estate agent as they are the one who helped draw the contract up, all of us would just be speculating.
Shane Milne | Lending in all 50 states | NMLS #81195