You just need to rebuild resp. reinstall libpdfium-nojs. It is a package with a dynamic version number, which means that it pulls the latest source code and determines the version number out of source code. Which is a higher version number than what you see in AUR.
Example:
AUR has
aur/libpdfium-nojs 5060.r1.558516c323-1
But the version I have istalled is
libpdfium-nojs 5249.r4.c5f61025a7-1
And that happened simply by reinstalling libpdfium-nojs