Absolutely. With respect to the 1984 study, that has been joined by significant amounts of research into school bus safety, which has now been published on Transport Canada's website. The 1984 study had conducted and presented the results of a literature survey, as well as discussions with stakeholders. It summarized a crash test program with three school buses and also explained the results of the tests, indicating potential for greater head injury if lap belts were installed.
Subsequently, to answer your question, there were significant technological advances and additional research that led to the technical specifications for the school bus regulations introduced in July 2018. These technical specifications included requirements, for example, for three-point seat belts, as well as to ensure that the seats on schools buses would be well and thoroughly anchored.