any issues booking on bahn.de from USA?

Where you are when you book should not be an issue. The internet is worldwide.
Booking with a non-European credit card may be an issue.

This will register as a transaction in Germany, in Euros. If you intend to use a US credit card, you need to contact your credit card company and ensure they will not block this as a suspicious foreign transaction.
Once you have informed your bank, try it and see if it works.

There have been reports of issues with some US Visa and Mastercards which do not have enhanced security, such as Verified by Visa. But I had no trouble booking Sparpreis tickets from Munich to Ljubljana using my American Express. They did text me to ask if it was a valid transaction, and once I confirmed, it went through.

I never had a problem, although I have not bought any in the last year. As Chris suggested, let your credit card co know you are making a foreign transaction. Give it a try. Get back to us if you have a problem.

thanks. Tickets are not available yet. I wanted to know if there were any issues b/c I will be picking my in/out cities based upon likely affordable train travel (for 5 persons). I will need to choose cities prior to tickets being offered. Being able to book a saver fare is hundreds of dollars less. I might do a test of a really cheap ticket, though.

www.trainline.eu has the same prices as DB, and easier credit card vetting. When you buy a ticket there, you get the actual DB print-at-home ticket emailed to you.

For this year's trip I booked from SF on bahn.de two discount tickets, 92 days or so prior to departure date, Frankfurt to Paris, 1 st class, and Munich to Frankfurt, 2nd class, got the lowest price available, used a Visa card for payment. The transactions went through.

I've had no problem the three times I've done it. Be sure to have the credit card you use with you. The conductor might want to see it although the last time he didn't.

Be sure to have the credit card you use with you. The conductor might want to see it although the last time he didn't.

That rule has been abandoned, you can show any piece of ID (passport, ID card, credit card, BahnCard).

You can also use Paypal.
https://www.bahn.com/en/view/booking-information/booking/paypal.shtml

I would be careful with Trainline. Use the Bahn website if you can. I've found situations where not applying Länder tickets correctly, or not recognizing all Bahnhofs, gives fares that are not the lowest possible.