I am preparing an update. I found out that the replacer also moved screenshot.png, which could be one reason of why some people are getting the error of it not working properly. The next update will fix this for you.
Also, due of how Blockland profile system broke some versions ago, I've added three variables that makes it possible to disable replacing of some parts. This will keep most of the replacing that GUI Replace offers, without you are forced to restart. However, it will display that you need to restart anyway, but this is optional.
There will also be a fix for replacing skins in folders, as that was somehow disabled and didn't worked at all. Although, I am also working on fixing the replacement of add-on skins, but I don't know if that will work as I thought it should.
And no... I am not dead nor have left this to die.

Edit: Add-Ons custom skin does not work. I don't know if I will remove it, but maybe disable it for now.