Hi,
No problem. Our previous EFM32 package was based on an older Gecko SDK (4.0.2). We have just updated it based on the latest release from Github (4.2.4, 32-bit SDK version 6.4.4).
If you would like to use the SDK files that are not included in the BSP, you can manually clone the SDK (make sure you are using the same version) and add the files to the project. If you would like to pull some of the libraries from the SDK into the BSP so that they could be added via VisualGDB GUI, you can patch our EFM32 BSP Generator. It currently only wraps the most basic libraries.
We also updated our EFM32 tutorial showing the new VisualGDB GUI and explaining how to find the SDK version.