Van Amersfoort admitted he was "scared" that the accident had been caused by a mechanical failure in one his cars.
"When we knew there was no longer life threatening, we went to analyse what had happened," he added.
"At first, you're scared because there were rumours that her brakes didn't work. Then you start to doubt yourself. In the end we gradually got to know what had happened.
"Sometimes you can despise social media, but now there was a lot that we otherwise would never have known.
"The FIA seized the onboard images of Sophia's camera and all the riders around her so we don't have to expect much help from them. Today we really got to know what exactly happened.
"And then I can only draw one conclusion: Dear God, everyone had an angel on their shoulders, because it could have ended much worse."
Floersch suffered a spinal fracture in the accident and underwent over nine hours of surgery on Monday to repair the vertebra and remove a bone splinter, which was sitting dangerously close to her spinal cord, according to the team.
Van Amersfoort said the initial signs suggested Floersch will have a positive recovery.
"Nerve monitoring shows that her vital nerve functions react well, therefore the initial signs give a positive outlook towards her recovery," the team said in a statement.