The best informaion I can offer is this... if your tranny didn't fail after it switched to aftermarket fluid and that fluid is still available, then don't worry.
Amsoil still approve their synthetic Multi ATF fluid for our 5HP30.
My tranny still has the Pennzoil Multi-ATF in the 5HP30 for over 30,000 miles and 10 years now... zero problem. Heck, if you put wrong fluid in that is not compatible, it probably will self destruct within a month. If it didn't, the fluid is compatible.