Tshite clocked 3:31.35 to finish ninth at the Diamond League meeting in Paris, surpassing Cronje’s 2013 time of 3:31.93 set in Italy.
Speaking to SABC Sport, Sepeng said he wasn’t surprised by the performance, adding that they were confident the record would fall if everything went according to plan.
"I'm very proud of him. Tshepo has been trying for a very long time to break the record, and he eventually did. We changed our tactics and how we are prepared after a disappointing campaign in Rabat, and it has clearly yielded great results," said the renowned athletics mentor.
The 28-year-old has already secured his spot at the World Senior Championships set to take place in Tokyo, Japan, later this year.
His coach has set a clear goal for him, and that is to reach the final of the 1500m event at the global showpiece in September.
"The World Championships are a completely different kettle of fish. We will keep on working and improving until then."
The South African 1500m champion took part in an invitational meet in the United States and also competed at the Rabat Diamond League in Morocco, but fell short of challenging the national record on both occasions.
However, his coach remained confident that the right moment to break the record would eventually arrive.
The 2018 South African Coach of the Year says they will base their training camp at the University of Pretoria, citing budget constraints as the reason for not heading to Europe, where many top-tier competitions and elite athletes are preparing for the World Championships.
"We will keep our camp in South Africa because we simply cannot afford to go overseas right now. We can only focus on what we can do and control, and that's what we're doing.
"We have found ourselves in this situation before, so we will just remain positive."