The full extent of its consequences would not be known for some time, prosecutor Sergeant Adrian Cheyne said.
When spoken to by police after the incident, Zhang told them he thought he had left enough room and was unaware he had made contact with Mr Gendron.
Attending the hearing was the victim's 31-year-old son Marc and his daughter Isabelle (29).
Marc Gendron said his father was "pretty stable", though was still being supported with feeding tubes and oxygen while in intensive care.
Discussions were being held between hospital representatives and Canadian government employees about transporting Mr Gendron home in an air ambulance, he said.
The family had provided a court with a list of the costs they had incurred as a result of the collision, but Judge Michael Turner said it was unlikely they would all be met.
"We totally understand that," Marc Gendron said.
Defence counsel Anne Stevens said her client was self-employed and "not well off" - making about $40,000 a year.
He would spent the next few days organising the most substantial payment he could, she said.
A couple of days after the incident, Zhang arranged for a card and a fruit basket to be delivered to the hospital, the court heard.
Mrs Stevens said her client wanted to meet the family of the victim for a restorative-justice conference before both parties left the country.
Mr Cheyne asked that, despite the guilty plea, no conviction was entered against Zhang because of Mr Gendron's still precarious health.
"He's not out of the woods yet, so to speak," the prosecutor said.
Zhang will be sentenced on Friday.
Judge Turner asked for an updated statement from the victim's family and one from medical staff concerning Mr Gendron's prognosis.
