As stated on the requirements page, the current version of Transcelerator does work with Paratext 8. However, when Transcelerator is installed, it detects existing versions of Paratext and asks which one(s) it should plug into. So if you have installed Paratext 8 after installing Transcelerator, you’ll need to re-install it. You probably have to uninstall the existing version first and then re-install; otherwise it will just think you’re wanting to update the existing version (in Paratext 7) and it probably won’t ask about installing into Paratext 8.