I has quickly looked at the Vegas Pro 16 release notes, and at the first grasp and a bit of searching i couldn't find these, so i wouldn't risk & i'll try to write 'em up here:
- Magic Wand / Flood Fill - Few months ago i have found and tries to use this (marked answer) .Net code, and was quite surprised none of the OFX sets i've found disposed them
- Removing of rotation 180° limitation in VFX - When i keyframed angles 0° and 360°, it actually stayed at 0° the entire time, so i had to add 180° inbetweeners (and the problem got bigger at higher angles..)
- Repeated keyframes - Sometimes i had to copy & paste keyframes over 'nd over, so ya could implement repeating mode where the keyframes would, for example, repeat 'till end of the clip
So far all i think of..