No, the Plant Factory assets are trainz build 5.6 which is supported by your build. However, there may be additional features implemented in this new build.
You will be able to install them and have a look at them, but it highly recommended they only be used in a route after the update. If you try to bulk replace them using an older build, it will cause rendering issues.
I've installed the update and I appear to having the same issues as others have reported. The track, in particular, is not appearing correctly. Performance is down ~20%.
The first video from my WIP route is from build 129343:
The next video shows the same scene in 131950 (note: the power station and QEII bridge don't appear):
The final video is something that caught my eye whilst not moving over a scene. It's stuck in a constant loop:
Note: all settings are the same between the builds, including draw distance of 22km.