There's still no pre-load function in LSL for animations. I know you can fiddle with using different priorities (https://wiki.secondlife.com/wiki/Category:LSL_Animation), but with dozen or more animations in an object that's just not a realistic solution. Others have tried overlapping animations or playing with animesh. Another possible solution used by dance performers to have their avatars run through all of the animations before going out on stage.
All of these work-arounds are either not practical in most cases or clunky in application. On the webpage linked above, there is a reference to "SVC-6866A llPreloadAnimation() - a function to preloading animations ready to be played on-demand without delay."
I know that the SVD-6866A request has been around for years (2010 or before). A pre-load function would be huge help to animators and make SL animations running smoother and more efficiently.