It doesn't work in the later versions of OpenSim Creator because, upstream, OpenSim has made GeometryPath a virtual base class for function-based paths etc., but OpenSim Creator's implementation for figuring out which property editors to show is doing something like typeid(property) == typeid(OpenSim::GeometryPath).
Mentioned in a LinkedIn conversation: https://www.linkedin.com/feed/update/urn:li:activity:7149008076111499264/?commentUrn=urn%3Ali%3Acomment%3A(ugcPost%3A7149008027994460160%2C7150112672095621122)&dashCommentUrn=urn%3Ali%3Afsd_comment%3A(7150112672095621122%2Curn%3Ali%3AugcPost%3A7149008027994460160)&dashReplyUrn=urn%3Ali%3Afsd_comment%3A(7150195240346247168%2Curn%3Ali%3AugcPost%3A7149008027994460160)&replyUrn=urn%3Ali%3Acomment%3A(ugcPost%3A7149008027994460160%2C7150195240346247168)
And it's a feature that should already be shipped+working: https://opensimcreator.com/video/gallery/0.4.1_Showcase.mp4
It doesn't work in the later versions of OpenSim Creator because, upstream, OpenSim has made
GeometryPatha virtual base class for function-based paths etc., but OpenSim Creator's implementation for figuring out which property editors to show is doing something liketypeid(property) == typeid(OpenSim::GeometryPath).