He most certainly did
.
Although Chang was primarily a Shuai Jaoi stylist, he took Yang Style Tai Chi and created Ch'ang Style Tai Chi. The primary difference being that he made it where most postures have a Shuai Jaoi throw application.
He also created a Hebei style off-shoot he called Hsing-Jing. Outwardly, it looks nearly identicle to Hebei style, but is altered slightly to include Shuai Jaoi applications.
Unfortunately (for me), the school I originally learned at taught Hebei style as fundamental training and only taught Hsing-Jing to its advanced students. So I can't really speak for Hsing-Jing itself, other than what I've learned from talking to the advanced students.
But yes, long winded answer for "Yes, GM Chang did learn and teach XY"