If I remember correctly, they technically still work but will be converted into the new planet classification system.
Detailed information can be found here: http://spaceengine.org/news/blog170924/
But essentially, the new classes are Terra, Ferria, Aquaria, Carbonia, Jupiter, and Neptune. The link I posted gives a good explanation as to why the system was changed and what the new classes represent.
If you want to be as accurate as possible, I suggest using the new class system. Hope this helps!