FYI here is a new review / comparison that mentions the new Apache Jena GeoSPARQL effort in this recent publication:
Assessment and Benchmarking of Spatially Enabled RDF Stores for the Next Generation of Spatial Data Infrastructure by Weiming Huang,Syed Amir Raza,Oleg Mirzov and Lars Harrie ISPRS Int. J. Geo-Inf. 2019, 8(7), 310; https://doi.org/10.3390/ijgi8070310 Enjoy, Marco -- --- Marco Neumann KONA
