Thanks! Yeah Puzzlescript probably isn't the best engine, but I may come back eventually and try to rework the controls one more time + add a level selector from one of the PS forks. I also wish that level solutions could be saved and rewatched later (or even have stats, so you can compare yourself to the fastest or cheapest possible solution).
The one you got stuck on is #19. If you want a hint: After pressing the button, first move yellow into place on the joiner.
As for the spoiler hint, I added some custom CSS to this page that turns strikethrough into spoilers:
del {
text-decoration: none !important;
background-color: #000000;
}
del:not(:hover) {
color: transparent;
}