I doubt the issues with this contract have anything to do with the origin of the parts. In fact, they have approximately 70% US content with the rest originating mostly from Europe. My sense is that these issues are all related to assembly at the Springfield plant. Here's an analogy of what I think is happening:
Your company needs 100 new computers with the stipulation that they be assembled inside your office. You receive proposals from Dell, HP, Lenovo, and some unknown XYZ company. XYZ company proposes the lowest price with the best parts from reputable brands (Intel, Asus, Corsair, etc.), but has never assembled a PC in your office before nor do they have a presence in your country. Fast forward a few months later and they've hired and trained a few assemblers and have started assembling your computers with parts coming in from all around the US. When these computers are submitted to you for inspection, you find that many of them have disconnected power supply cables, missing screws, memory modules arranged incorrectly, and all sorts of other assembly quality issues. You complain to the company, they say they're rectifying these issues, and you continue to find things that are wrong with every completed unit, delaying your project by months.
One saving grace to the scenario above is that these parts are all standardized, and anyone with computer assembly experience can finish the job. I'm not sure how standardized railcar parts or designs are, so in the event that the T terminates the contract, I'd be interested in seeing if they can find another company to assemble them.