what you have now is the latest official GOG update (meaning, the latest update that got picked up by GOG and wrapped up in the official installer). I have linked the next/newer update, which includes a newer version of the NewDark engine. I've put it together quite a while ago, hoping that GOG would make it official, just like they did with the previous patch I've gave them (the one you are using now). they didn't so far, so I guess it has low priority.
anyway, the easiest way of staying up to date is
TFix, but some people are paranoid about 3rdparty stuff, that's why I'm also putting together the basic patches for GOG each time the engine gets updated, so they can make it official if they want and make those people happy. does not change the fact that it's all 3rdparty stuff, it has always been, and it always will be.
to make it short, just patch up with TFix and unicorns and rainbows are guaranteed.